Multiple sctp associations per s1ap connection and moving s1ap signaling connection between sctp associations

ABSTRACT

Certain embodiments disclose systems, methods, and apparatus for establishing and using multiple Stream Control Transmission Protocol (SCTP) associations. An example method includes a network node establishing a first SCTP association and a second SCTP association for an application protocol connection with a core network node. The network node moves a user equipment (UE) associated signaling stream from the first SCTP association to the second SCTP association.

PRIORITY

This application is a continuation of U.S. application Ser. No.16/092,897 entitled “MULTIPLE SCTP ASSOCIATIONS PER S1AP CONNECTION ANDMOVING S1AP SIGNALING CONNECTION BETWEEN SCTP ASSOCIATIONS” filed Oct.11, 2018, which is a 371 of International Application No.PCT/IB2017/051957, filed Apr. 5, 2017, which claims the benefit ofpriority from U.S. Provisional Application No. 62/321,530 filed Apr. 12,2016 and U.S. Provisional Application No. 62/321,570 filed Apr. 12,2016, the disclosures of which are hereby incorporated herein in theirentirety by reference.

TECHNICAL FIELD

Certain embodiments of the present disclosure relate to a method, node,apparatus, and/or system for supporting multiple Stream ControlTransmission Protocol (SCTP) associations per S1 Application Protocol(S1AP) connection and control thereof.

BACKGROUND

The third generation partnership project (3GPP) is currently working onstandardization of Release 13 of the Long Term Evolution (LTE) concept.An example LTE system is shown in FIG. 1. The LTE architecture shown inFIG. 1 includes radio access nodes, such as enhanced Node Bs (eNBs),Home eNBs (HeNBs), and an HeNB Gateway (GW). The LTE architecture shownin FIG. 1 also includes evolved packet core nodes, such as MobilityManagement Entities/Serving Gateways (MME/S-GW). FIG. 1 further showslogical interfaces between the various nodes. As shown, an S1 interfaceconnects HeNBs/eNBs to the MME/S-GW. An S1 interface is also shownconnecting HeNBs to the HeNB GW. As shown, an X2 interface connects peereNBs/HeNBs, optionally via an X2 GW. The radio access nodes maycommunicate wirelessly with user equipment (UEs) (not shown), as furtherdiscussed below.

FIG. 2 illustrates an example of a management system that may be assumedfor purposes of discussing certain embodiments of the solutions proposedherein. The node elements (NE), also referred to as eNodeB, for example,are managed by a domain manager (DM), also referred to as the operationand support system (OSS). A DM may further be managed by a networkmanager (NM). Two NEs are interfaced by X2, whereas the interfacebetween two DMs is referred to as Itf-P2P. The management system mayconfigure the network elements and may receive observations associatedwith features in the network elements. For example, the DM observes andconfigures NEs. The NM observes and configures the DM. The NM can alsoconfigure the NE via the DM. The configuration performed via the DM, NM,and related interfaces allow for carrying out functions over the X2 andS1 interfaces in a coordinated way throughout the RAN, eventuallyinvolving the Core Network, i.e., Mobility Management Entity (MME) andServing Gateways (S-GWs).

FIG. 3 illustrates an example of an S1 Interface Control Plane stack.The S1 Control Plane interface is defined between MME and eNB, and isdescribed in 3GPP specifications TS 36.300, TS 36.410, TS 36.411, TS36.412 and TS 36.413. The transport network layer is based on InternetProtocol (IP) transport with an SCTP layer added on top of IP. The SCTPlayer provides reliable transport of signaling messages. According tothe existing 3GPP specifications, only one single SCTP association isestablished between one MME and eNB pair. Within the SCTP associationestablished between one MME and eNB pair, one single pair of streamidentifiers shall be reserved for the sole use of S1AP elementaryprocedures that utilize non UE-associated signaling, at least one (andup to a few) pair of stream identifiers are reserved for the sole use ofS1AP elementary procedures that utilize UE-associated signaling. Also, asingle UE-associated signaling shall use one SCTP stream and the streamshould not be changed during the communication of the UE-associatedsignaling.

FIG. 4 shows a state transition diagram of S1AP. In case the SCTP layernotifies the S1AP layer that the signaling connection broke, the entireS1AP will then be reset on both endpoints. That is, the MME locallychanges the state of the UEs which used this signaling connection to theECM-IDLE state, and the eNB releases the Radio Resource Control (RRC)connection with those UEs. This is reflected in the state diagram asarrow from S1AP CONNECTED to S1AP DISCONNECTED with action “Broken lowerlayer.”

FIG. 5 illustrates the S1 setup procedure (successful operation). Duringthe procedure, the endpoints (MME and eNB) will erase all existingapplication level configuration data and replace it by the one receivedin the procedure. This procedure also re-initializes the E-UTRAN S1APUE-related contexts (if any) and erases all related signalingconnections for the endpoints. This is reflected in the state diagram ofFIG. 4 as the arrow from S1AP DISCONNECTED to S1AP CONNECTED with action“S1 SETUP” (in case of no application level configuration data, ortransport layer has been broken before), or as the arrow from S1APCONNECTED to S1AP CONNECTED with action “S1 SETUP” (in case of previousapplication level configuration data and transport layer is not broken).

Currently, there is no procedure to tear down an S1AP connection. Inpractice this means S1AP may be torn down only by breaking the signalingconnection. This is reflected in the state diagram as arrow from S1APCONNECTED to S1AP DISCONNECTED with action “Broken lower layer.”

As discussed above with respect to FIG. 3, the S1 Interface ControlPlane stack includes an SCTP layer. Stream Control Transmission Protocol(SCTP) is a reliable transport protocol operating on top of aconnectionless packet network such as IP. SCTP offers a number ofservices to its users. For example, SCTP offers acknowledged error-freenon-duplicated transfer of user data. As another example, SCTP offersdata fragmentation to conform to discovered path MTU size. As anotherexample, SCTP offers sequenced delivery of user messages within multiplestreams, with an option for order-of-arrival delivery of individual usermessages. As yet another example, SCTP offers optional bundling ofmultiple user messages into a single SCTP packet. As a final example,SCTP offers network-level fault tolerance through supporting ofmulti-homing at either or both ends of an association. The design ofSCTP also includes appropriate congestion avoidance behavior andresistance to flooding and masquerade attacks.

FIG. 6 illustrates an example SCTP association initialization procedure.More particularly, FIG. 6 is a signal-flow diagram of an initializationof SCTP association between endpoints (client 602 and server 604). Atstep 606, client 602 sends an initialization (INIT) message to server604. At step 608, server 604 sends an initialization acknowledgementmessage (INIT-ACK) message to client 602. At step 610, client 602 sendsa COOKIE-ECHO message to server 604. At step 612, server 604 sends aCOOKIE-ACK message to client 602.

During the four-way handshake performed during initialization, thefollowing SCTP specific information is exchanged between the endpoints(i.e., client 602 and server 604). The exchanged information includes aninitiated tag, an advertised receiver window credit, a number ofoutbound streams, a number of inbound streams, an initial transmissionsequence number (TSN), and a state cookie.

The Initiated Tag is used for packet validation of the SCTP session. Atag value (initial tag) is chosen by each end of the association duringassociation initialization. This value will be assigned to field“Verification Tag” on all upcoming packets. Packets received without theexpected Verification Tag value in the session are discarded, as aprotection against blind masquerade attacks and against stale SCTPpackets from previous sessions.

The Advertised Receiver Window Credit parameter represents the dedicatedbuffer space, in number of bytes, the endpoints have reserved inassociation with this window. During the life of the association, thisbuffer space should not be lessened (i.e., dedicated buffers taken awayfrom this association).

The number of outbound streams defines the number of outbound streamsthe sender endpoint wishes to create in this association. The finalnumber of outbound streams will be the minimum value of “Number ofOutbound Streams” from the sender endpoint and the “Number of InboundStreams” from the receiver endpoint.

The number of inbound streams defines the maximum number of streams thesender endpoint allows the peer end to create in this association. Thefinal number of inbound streams will be the minimum value of “Number ofInbound Streams” from the sender endpoint and the “Number of OutboundStreams” from the receiver endpoint.

The Initial TSN is the initial TN of the sender of the association.

The state cookie is used for session authentication for protectionagainst attack.

For multi-homing, in the current SCTP standard, multiple transportaddresses on the end-points can be setup during the associationinitialization procedure. Modification of addresses after SCTPestablishment can be done with an INIT message and a new address listparameter, the receiving endpoint responds with an ABORT message withcause of error “restart of an association with new addresses.” Thesignal flow for address changes is described in more detail below inrelation to FIG. 7.

FIG. 7 illustrates an example of address changes on an existingassociation. More particularly, FIG. 7 is a signal-flow diagram of anaddress change between endpoints (Endpoint A 702 and Endpoint Z 704). Atstep 706, Endpoint A 702 sends an INIT message to Endpoint Z 704. TheINIT message includes a new address list parameter (reflected in theexample of FIG. 7 as “address list=<differ from previousINIT/INIT-ACK>”). At step 708, Endpoint Z 704 sends an ABORT message toEndpoint A 702. The ABORT message includes a cause of error “restart ofan association with new addresses” (reflected in the example of FIG. 7as “Error Cause=“Restart of an association with new addresses”).

FIG. 8 illustrates a simplified procedure for a (graceful) terminationof SCTP association. In FIG. 8, Endpoint A wants to terminate theassociation. Endpoint A will stop accepting new data from its upperlayer. Endpoint A will wait (and retransmit outstanding data if needed)until all outstanding data has been acknowledged by Endpoint Z. EndpointA then transmits a SHUTDOWN chunk to Endpoint Z. When Endpoint Zreceives the SHUTDOWN chunk, it will stop accepting new data from itsupper layer. Endpoint Z will wait (and retransmit outstanding data ifneeded) until all outstanding data has been acknowledged by Endpoint A.Endpoint Z then transmits a SHUTDOWN-ACK chunk to Endpoint A. WhenEndpoint A receives the SHUTDOWN-ACK chunk, it will remove all record ofthe association and will transmit a SHUTDOWN-COMPLETE chunk to EndpointZ. When Endpoint Z receives the SHUTDOWN-COMPLETE chunk, it will removeall record of the association.

The present disclosure proposes solutions that may be applied to an S1interface, such as the S1 interface in the LTE architecture. The LTEarchitecture may evolve over time. The overall principles of thesolutions proposed herein would work for both an LTE-like architectureand a new architecture based on an evolution of the S1 interface, forexample, an architecture with evolved counterparts of the S1, X2 and Uuinterfaces and which further provides that any new Radio AccessTechnology (RAT) would be integrated with the LTE radio interface at RANlevel in a similar fashion as the way LTE Dual Connectivity is defined.An example of an evolved architecture is a 5G architecture.

LTE and evolutions thereof (such as 5G) may support various features andfunctionality. As an example, the concept of network slicing applies toboth LTE Evolution and new 5G RAT (also referred to as “NX” herein).Network slicing is about creating logically separated partitions of thenetwork, addressing different business purposes. These “network slices”are logically separated to a degree that they may be regarded andmanaged as networks of their own. A key driver for introducing networkslicing is business expansion, such as improving the cellular operator'sability to serve a number of different industries, e.g., by offeringconnectivity services with different network characteristics(performance, security, robustness, and complexity).

FIG. 9 illustrates an example of an architecture with network slicing.As shown, a shared Radio Access Network (RAN) infrastructure connects toseveral Evolved Packet Core (EPC) instances (one EPC instance pernetwork slice). As the EPC functions are virtualized, an operator mayinstantiate a new Core Network (CN) when it is determined that a newslice should be supported. Slice 0, for example, may be a MobileBroadband slice and Slice 1, may, for example, be a Machine TypeCommunication network slice.

SUMMARY

Certain problems may occur as a result of using previous techniques forestablishing an SCTP association. As discussed above, previoustechniques establish only a single SCTP association between an eNB andMME. As a result, a first problem that may be associated with previoustechniques for establishing an SCTP association is that UEs supported bythe single SCTP association may lose connectivity to the network if afailure occurs on the single SCTP association.

A second problem that may be associated with previous techniques forestablishing an SCTP association is an inability to provide a gracefulredundancy switch of hardware (HW) in the case of a hardware swap. It isdesired that during hardware maintenance and/or expansion, the ongoingtraffic in the network should be maintained without disturbance (e.g.,without packet loss). However, with the current limitation of S1AP/SCTPrelationship, and the current S1AP protocol, it is not possible to swapthe hardware where the SCTP/S1AP software is located withoutdisconnecting all the UEs connected to the S1AP connection.Unfortunately Multi-homing is not a solution as it does not solve theproblem if the SCTP process instance that needs to be swapped is locatedin hardware.

A third problem that may be associated with previous techniques forestablishing an SCTP association occurs when a single UE handlingfailure causes a domino crash of SCTP. During SCTP associationinitialization, a common receiving buffer is assigned (reflected byparameter Advertised Receiver Window Credit). This receiving buffer willbe the shared resource between the SCTP user application (i.e., S1AP)and SCTP transport service. As the receiving buffer is the sharedresource between SCTP transport service and S1AP service, communicationcrash between an MME and an eNB will occur as soon as crash occurs onone single process in SCTP user application or SCTP transport service(e.g., one of the UE handling processes). Unfortunately, introduction ofstreams within SCTP instance will not solve this problem as thereceiving buffer is shared among the streams. This lack of robustness isespecially serious when the eNB has a big configuration with contains alot of connecting UEs.

A fourth problem that may be associated with previous techniques forestablishing an SCTP association occurs during high S1 signalingintensity. It is possible that an eNB or future evolutions of it maycover wide areas with its cells. With this evolution of eNBs, it mayoccur that an eNB may serve a large number of UEs and therefore generatea large amount of S1AP traffic towards connected MMEs. One problem thatmay occur in such scenario is that a single SCTP association between theeNB and one of the connected MME will have to carry a very large amountof S1AP traffic, resulting in scalability problems. Namely the nodesterminating the SCTP association supporting the S1AP traffic may becomeoverloaded with the large amount of S1AP signaling.

Certain embodiments of the present disclosure may provide solutions toone or more problems associated with previous techniques forestablishing an SCTP association. For example, certain embodimentsintroduce procedures in which multiple SCTP association instances areallowed to be associated to a single S1AP. These multiple SCTPassociation instances may be dynamically added and removed during thelifetime of S1AP. To apply the proposed solution to the current S1APinterface would require changes to the current S1AP interface. Thesolution may also be applied to other interfaces, such as the X2APinterface or other 3GPP interfaces that use single SCTP associationinstance as Transport Network Layer (TNL).

Certain embodiments disclose a method for use in a first network node.The method comprises establishing a first Stream Control TransmissionProtocol (SCTP) association for an S1AP connection between the firstnetwork node and a second network node and connecting the S1APconnection between the first network node and the second network node.The method further comprises establishing a second SCTP association forthe S1AP connection between the first network node and the secondnetwork node.

Certain embodiments disclose a network node. The network node comprisesan interface operable to facilitate communications with a second networknode, a memory operable to store instructions, and processing circuitryoperable to execute the instructions that cause the node to connect anS1AP connection between the first network node and the second networknode and to establish first and second SCTP associations for the S1APconnection. In certain embodiments, the network node further comprises adetermining module, a communication module, and a receiving module. Thedetermining module determines to establish the first and second SCTPassociations. The determination may be initiated by the network nodeitself, or may be made in response to a request from the second networknode to establish an SCTP association. In certain embodiments, thedetermining module also determines to move traffic from the first SCTPassociation to the second SCTP association, for example, in response toa load balancing determination, in connection with hardware maintenanceor hardware expansion, or in response to a determination to performnetwork slicing. The determining module sends signals or messages to thecommunication module to facilitate establishing the SCTP associationsand/or moving the traffic, and the communication module communicates thesignals or messages to the second network node. The receiving modulereceives signals or messages from the second network node and maycommunicate the received signals or messages to the determining modulefor use in further determinations.

Certain embodiments disclose a computer program product comprising anon-transitory computer readable storage medium having computer readableprogram code embodied in the medium. The computer readable program code,when executed by a first network node, is operable to connect an S1APconnection between the first network node and a second network node andto establish first and second SCTP associations for the S1AP connection.

The first and second SCTP associations in the above-described method,network node, and computer program product can be used to carry traffic.The traffic can be carried on a plurality of signaling streams, and thesignaling streams can be allocated among the SCTP associations in anysuitable manner. For example, in certain embodiments, theabove-described method, network node, or computer program productdedicates the first SCTP association to one or more user equipment (UE)associated signaling streams and dedicates the second SCTP associationto a non-UE associated signaling stream. In the example, each UEassociated signaling stream is associated with a respective UE. As analternative example, the above-described method, network node, orcomputer program product associates a first non-UE associated signalingstream and a first set of one or more UE associated signaling streamswith the first SCTP association, and associates a second non-UEassociated signaling stream and a second set of one or more UEassociated signaling streams with the second SCTP association.

An advantage of the above-described method, network node, and computerprogram product is that by allowing multiple SCTP associations per S1APconnection, the proposed solution can eliminate resetting of all UEsassociated to S1AP in case of re-establishment of S1AP transport layer(SCTP) during e.g., hardware (HW) maintenance/expansion, as the SCTPassociation may now be disconnected and reconnected to S1AP withoutremoval of existing S1AP configuration data. An additional advantage isthat the proposed solution increases S1AP robustness in case of softwarefailure (SW_failure), that is, the number of affected UEs will bedecreased when a SCTP instance fails. A further advantage of theproposed solution is that is allows for S1AP signaling load distributionby spreading signaling load over multiple SCTP connections eventuallyserved by different processors.

In further embodiments of the above-described method, network node, andcomputer program product, traffic is moved from the first SCTPassociation to the second SCTP association. The traffic comprises userequipment (UE) associated S1AP control signaling and/or non-UEassociated S1AP control signaling. The ability to move from one SCTPassociation to another may provide additional technical advantages. Forexample, traffic can be moved in response to a load balancingdetermination, in connection with hardware maintenance or hardwareexpansion, or in response to a determination to perform network slicing.

Another technical advantage of certain embodiments allows for gracefulshutdown of an SCTP association, which may allow for graceful moving ofS1AP signaling between SCTP associations. As an example, theabove-described method, network node, and computer program product cansend outgoing S1AP messages on the second SCTP association afterstopping outgoing S1AP messages on the first SCTP association andconfirming that incoming S1AP messages on the first SCTP associationhave stopped.

As a more specific example, from the perspective of a network node thatinitiates moving the traffic, the method, network node, or computerprogram product can stop all outgoing S1AP messages on the first SCTPassociation and, after stopping all the outgoing S1AP messages, send thesecond network node a request to move from the first SCTP association tothe second SCTP association. The request comprises a first stop markerindicating the last message being transmitted by the first network nodeon the first SCTP association. The method, network node, or computerprogram product then receives from the second network node aconfirmation to move the first SCTP association to the second SCTPassociation. The confirmation comprises a second stop marker indicatingthe last message being transmitted by the second network node on thefirst SCTP association. After receiving the confirmation, the method,network node, or computer product uses the second SCTP association tosend the outgoing S1AP messages occurring after the first stop markerand to receive incoming S1AP messages occurring after the second stopmarker.

As a more specific example, from the perspective of a network node thatdoes not initiate moving the traffic, the method, network node, orcomputer program product receives from the second network node a requestto move from the first SCTP association to the second SCTP association.The request comprises a first stop marker indicating the last messagebeing transmitted by the second network node on the first SCTPassociation. In response, the method, network node, or computer programproduct stops all outgoing S1AP messages on the first SCTP associationand then sends the second network node a confirmation to move the firstSCTP association to the second SCTP association. The confirmationcomprises a second stop marker indicating the last message beingtransmitted by the first network node on the first SCTP association. Themethod, network node, or computer program product receives an indicationfrom the second network node that the move to the second SCTPassociation is complete. The indication can comprise a completionmessage or the receipt of incoming S1AP messages via the second SCTPassociation. The incoming S1AP messages received on the second SCTPassociation comprise messages occurring after the first stop marker.

In certain embodiments having an S1AP connection with multiple SCTPassociations, it is desirable that only some of the S1AP signalingsmapped on a SCTP association be moved without causing disturbance onother signaling any of the SCTP associations, for example, in the caseof load balancing.

Certain embodiments of the above-described solutions introducesprocedures that allow a single S1AP signaling connection (bothUE-associated and non UE-associated) to be moved between SCTPassociations for an S1AP signaling connection with multiple SCTPassociations. To stop the S1AP signaling for an SCTP association, “StopMarker” messages (one originated from eNB, and one originated from MME)are introduced on S1AP. The usage of the “stop marker” messages issummarized as follows. First, the originating endpoint stops all theoutgoing messages for an individual UE-associated signaling instance ornon UE-associated signaling instance. Second, in some embodiments, theoriginating endpoint also transmits a “stop marker” message to thedestination endpoint using the same “signaling identity” through thesame stream the individual signaling instance. These “stop marker”messages acts as the last message for the SCTP signaling before thesignaling flow has been stopped on the old SCTP association. As SCTPguarantees in-order delivery of S1AP messages, after the “stop marker”message has been received, subsequent messages from the S1AP signalingmay then be moved to a new SCTP association which still guaranteesin-order delivery of messages without loss. For resuming the stoppedS1AP signaling, “Start marker” message is introduced on S1AP layer insome embodiments. This “start marker” message informs the endpoints thatthe S1AP message may be resumed on the new SCTP association. Theprocedure prevents disturbance on any levels of S1AP interface, i.e.,S1AP signaling and SCTP association.

An advantage of including stop and/or start markers when moving trafficinclude increased flexibility of load distribution capability in a S1APwith multiple SCTP associations, where a single S1AP signalingconnection may be freely moved between SCTP association without causingany disturbance on the interface in terms of in-order delivery, lostmessage, or reset of any SCTP association.

The above-described procedures may allow for moving some or all trafficfrom the first SCTP association. In an embodiment, all of the trafficfrom the first SCTP association is moved to the second SCTP associationand/or other SCTP association(s) between the first network node and thesecond network node. The first SCTP association may then be deletedafter moving all of the traffic from the first SCTP association. Anadvantage of this embodiment allows for performing maintenance on thehardware that was carrying the first SCTP association. In anotherembodiment, some of the traffic remains on the first SCTP association(i.e., the first SCTP association is not deleted), for example, in thecase of load balancing.

In certain embodiments, the traffic comprises a plurality of streams.The messaging between the first network node and the second network nodeidentifies one or more of the streams to move from the first SCTPassociation to the second SCTP association. As an example, the trafficmay comprise a plurality of user equipment (UE) associated signalingstreams, and the messaging between the first network node and the secondnetwork node comprises a list identifying at least two of the UEassociated signaling streams to move from the first SCTP association tothe second SCTP association.

An advantage of certain embodiments is that the traffic is moved fromthe first SCTP association to the second SCTP association without havingto tear down the S1AP connection.

In certain embodiments, identifiers are used to establish, delete, orreset the first SCTP association or to establish, delete, or move asignaling stream. The method, network node, or computer program productcan determine any suitable identifiers. In certain embodiments, theidentifiers include a first configuration identifier that the firstnetwork node associates with the S1AP connection, a second configurationidentifier that the second network node associates with the S1APconnection, a first bundle identifier that the first network nodeassociates with the first SCTP association, and a second bundleidentifier that the second network node associates with the first SCTPassociation. In certain other embodiments, the identifiers include afirst configuration identifier that the first network node associateswith the S1AP connection, a second configuration identifier that thesecond network node associates with the S1AP connection, a first bundleidentifier that the first network node associates with a signalingstream of the first SCTP association, and a second bundle identifierthat the second network node associates with the signaling stream of thefirst SCTP association.

As further discussed below, the proposed solutions requires changes inthe S1AP interface defined in the existing 3GPP specification. Theproposed solution may also be applied to X2 Application Protocol (X2AP)interface or other 3GPP RAN interface using SCTP as Transport NetworkLayer or evolutions thereof.

Certain embodiments may have all, some, or none of the technicaladvantages discussed above. Other advantages will be apparent to thoseof ordinary skill in the art.

BRIEF DESCRIPTION

FIG. 1 is a block diagram illustrating an example of an LTE networkarchitecture that includes S1 interfaces.

FIG. 2 is a block diagram illustrating an example of a management systemarchitecture that may be used to configure elements of a network.

FIG. 3 is a block diagram illustrating an example of an S1 InterfaceControl Plane stack that includes an SCTP layer.

FIG. 4 is a state diagram illustrating an example of S1AP statetransitions.

FIG. 5 is a signal diagram illustrating an S1 setup procedure.

FIG. 6 is a signal diagram illustrating an SCTP associationinitialization procedure.

FIG. 7 is a signal diagram illustrating an address change on an existingSCTP association.

FIG. 8 is a signal diagram illustrating a graceful termination of anSCTP association.

FIG. 9 is a block diagram illustrating an example of network slicing.

FIG. 10 is a block diagram illustrating an example of a wirelessnetwork, in accordance with certain embodiments of the presentdisclosure.

FIGS. 11-12 are diagrams illustrating examples of establishing multipleSCTP Associations per S1AP Connection and mapping non UE-associatedprocedures and UE-associated procedures to the SCTP associations, inaccordance with certain embodiments of the present disclosure.

FIG. 13 is a diagram illustrating assignment of S1AP identifiers todistinguish between main S1AP signaling connection and S1 signalingbundles on different SCTP instances, in accordance with certainembodiments of the present disclosure.

FIG. 14 is a signal diagram illustrating an example method for adding anSCTP association to an existing S1AP connection, in accordance withcertain embodiments of the present disclosure.

FIG. 15 is a signal diagram illustrating an example of an MME-initiatedmethod for adding an SCTP association to an existing S1AP connection, inaccordance with certain embodiments of the present disclosure.

FIG. 16 is a signal diagram illustrating an example of an eNB-initiatedmethod for adding an SCTP association to an existing S1AP connection, inaccordance with certain embodiments of the present disclosure.

FIG. 17 is a signal diagram illustrating an example of a method forgracefully deleting an SCTP association carrying non-UE associatedsignaling from S1AP, in accordance with certain embodiments of thepresent disclosure.

FIG. 18 is a signal diagram illustrating an example of a method forgracefully deleting an SCTP association carrying UE associated signalingfrom S1AP, in accordance with certain embodiments of the presentdisclosure.

FIG. 19 is a signal diagram illustrating an example of an MME-initiatedmethod for gracefully deleting an SCTP association from S1AP, inaccordance with certain embodiments of the present disclosure.

FIG. 20 is a signal diagram illustrating an example of an eNB-initiatedmethod for gracefully deleting an SCTP association from S1AP, inaccordance with certain embodiments of the present disclosure.

FIG. 21 is a signal diagram illustrating an example of a method forbroken SCTP association handling to existing S1AP, in accordance withcertain embodiments of the present disclosure.

FIG. 22 is a signal diagram illustrating an example of a method formoving multiple UE-associated signaling connections between SCTPassociations (successful case), in accordance with certain embodimentsof the present disclosure.

FIG. 23 is a signal diagram illustrating an example of an eNB-initiatedmethod for moving a single UE-associated signaling connection betweenSCTP associations (successful case), in accordance with certainembodiments of the present disclosure.

FIG. 24 is a signal diagram illustrating an example of an MME-initiatedmethod for moving a single UE-associated signaling connection betweenSCTP associations (successful case), in accordance with certainembodiments of the present disclosure.

FIG. 25 is a signal diagram illustrating an example of a method formoving a single UE-associated signaling connection between SCTPassociations (failure case), in accordance with certain embodiments ofthe present disclosure.

FIG. 26 is a signal diagram illustrating an example of a method formoving a non-UE associated signaling connection between SCTPassociations (successful case), in accordance with certain embodimentsof the present disclosure.

FIG. 27 is a signal diagram illustrating an example of an eNB-initiatedmethod for moving a non-UE associated signaling connection between SCTPassociations (successful case), in accordance with certain embodimentsof the present disclosure.

FIG. 28 is a signal diagram illustrating an example of an MME-initiatedmethod for moving a non-UE associated signaling connection between SCTPassociations (successful case), in accordance with certain embodimentsof the present disclosure.

FIG. 29 is a signal diagram illustrating an example of a method formoving a non-UE associated signaling connection between SCTPassociations (failure case), in accordance with certain embodiments ofthe present disclosure.

FIG. 30 is a flow chart illustrating an example of a method forestablishing multiple SCTP associations per S1AP connection, inaccordance with certain embodiments of the present disclosure.

FIG. 31 is a flow chart illustrating an example of a method forassociating UE-associated signaling streams and non-UE associatedsignaling streams with SCTP associations, in accordance with certainembodiments of the present disclosure.

FIG. 32 is a flow chart illustrating an example of a method forassociating UE-associated signaling streams and non-UE associatedsignaling streams with SCTP associations, in accordance with certainembodiments of the present disclosure.

FIG. 33 is a signal diagram illustrating an example of a method formoving traffic between SCTP associations, in accordance with certainembodiments of the present disclosure.

FIG. 34 is a flow chart illustrating an example of a method foridentifying an SCTP association, in accordance with certain embodimentsof the present disclosure.

FIG. 35 is a block diagram illustrating an example of a wireless device(e.g., UE), in accordance with certain embodiments of the presentdisclosure.

FIG. 36 is a block diagram illustrating an example of a network node(e.g., eNB), in accordance with certain embodiments of the presentdisclosure.

FIG. 37 is a block diagram illustrating an example of a network node(e.g., MME), in accordance with certain embodiments of the presentdisclosure.

FIG. 38 is a block diagram illustrating an example of a components of awireless device (e.g., UE), in accordance with certain embodiments ofthe present disclosure.

FIG. 39 is a block diagram illustrating an example of components of anetwork node (e.g., eNB or MME), in accordance with certain embodimentsof the present disclosure.

DETAILED DESCRIPTION

Certain embodiments of the present disclosure relate to establishingmultiple SCTP associations per S1AP Connection. For example, the presentdisclosure describes methods, network nodes, and computer programproducts for adding, (gracefully) deleting, and handling of a brokenSCTP association to an existing S1AP. Further embodiments relate tomoving UE-associated signaling and/or non-UE associated signalingbetween SCTP Associations. In addition, the present disclosure describesidentifiers that can be used to identify a mapping of individual SCTPassociation to S1AP. Particular embodiments are described with respectto FIGS. 10-39 of the drawings, like numerals being used for like andcorresponding parts of the various drawings.

FIG. 10 illustrates an example of a wireless network 100 in which theproposed solutions may be implemented, in accordance with certainembodiments. Network 100 includes one or more UE(s) 110 (which may beinterchangeably referred to as wireless devices 110) and one or morenetwork node(s), such as radio access nodes 120 (e.g., access point, aradio access point, a base station, a base station controller, an eNodeB(eNB), a Home eNB (HeNB), a HeNB Gateway (HeNB GW), etc.) and corenetwork nodes 130 (e.g., MMEs, S-GWs, or other device that supports oneor more SCTP-S1AP connections). Examples of interfaces between networknodes are described above (e.g., FIG. 1 and FIG. 3).

UEs 110 may communicate with radio network nodes 120 over a wirelessinterface. For example, a UE 110 may transmit wireless signals to one ormore of network nodes 120, and/or receive wireless signals from one ormore of network nodes 120. The wireless signals may contain voicetraffic, data traffic, control signals, and/or any other suitableinformation. In some embodiments, an area of wireless signal coverageassociated with a network node 120 may be referred to as a cell. In someembodiments, UEs 110 may have device-to-device (D2D) capability. Thus,UEs 110 may be able to receive signals from and/or transmit signalsdirectly to another UE.

In certain embodiments, radio access nodes 120 may interface with aradio network controller. The radio network controller may control radioaccess nodes 120 and may provide certain radio resource managementfunctions, mobility management functions, and/or other suitablefunctions. In certain embodiments, functions of the radio networkcontroller may be included in radio access node 120, core network node130, or both. Radio access node 120 may interface with core network node130 via an interconnecting network 125. Interconnecting network 125 mayrefer to any interconnecting system capable of transmitting audio,video, signals, data, messages, or any combination of the preceding.Interconnecting network 125 may include all or a portion of a publicswitched telephone network (PSTN), a public or private data network, alocal area network (LAN), a metropolitan area network (MAN), a wide areanetwork (WAN), a local, regional, or global communication or computernetwork such as the Internet, a wireline or wireless network, anenterprise intranet, or any other suitable communication link, includingcombinations thereof.

In some embodiments, the core network node 130 may manage theestablishment of communication sessions and various otherfunctionalities for UEs 110. UEs 110 may exchange certain signals withthe core network node using the non-access stratum layer. In non-accessstratum signaling, signals between UEs 110 and the core network node maybe transparently passed through the radio access network.

As described above, example embodiments of network 100 may include oneor more wireless devices 110, and one or more different types of networknodes capable of communicating (directly or indirectly) with wirelessdevices 110. In some embodiments, the non-limiting term UE is used. UEs110 described herein can be any type of wireless device capable ofcommunicating with network nodes or other UEs over radio signals. UE 110may also be a radio communication device, target device, D2D UE,machine-type-communication UE or UE capable of machine to machinecommunication (M2M), low-cost and/or low-complexity UE, a sensorequipped with UE, Tablet, mobile terminals, smart phone, laptop embeddedequipped (LEE), laptop mounted equipment (LME), USB dongles, CustomerPremises Equipment (CPE), etc.

The term network node can be any kind of network node, such as radioaccess node 120 or core network node 130. Examples of network nodesinclude a base station (BS), radio base station, Node B, multi-standardradio (MSR) radio node such as MSR BS, eNB, gNB, network controller,radio network controller (RNC), base station controller (BSC), relaynode, relay donor node controlling relay, base transceiver station(BTS), access point (AP), radio access point, transmission points,transmission nodes, Remote Radio Unit (RRU), Remote Radio Head (RRH),nodes in distributed antenna system (DAS), Multi-cell/multicastCoordination Entity (MCE), core network node (e.g., MSC, MME, etc.),O&M, OSS, SON, positioning node (e.g., E-SMLC), MDT, or any othersuitable network node.

The terminology does not imply a certain hierarchical relation betweenthe nodes. For example, certain embodiments may be described in terms ofa first network node and a second network node, these network nodes maybe any suitable network node. For example, in certain embodiments thefirst network node may be a radio access node 120 (e.g., eNB or gNB) andthe second network node may be a core network node (e.g., MME or S-GW).As another example, in other embodiments the first network node may be acore network node (e.g., MME or S-GW) and the second network node may bea radio access node 120 (e.g., eNB or gNB).

Example embodiments of UE 110 and network nodes 120 and 130 aredescribed in more detail below with respect to FIGS. 35-39.

Although FIG. 10 illustrates a particular arrangement of network 100,the present disclosure contemplates that the various embodimentsdescribed herein may be applied to a variety of networks having anysuitable configuration. For example, network 100 may include anysuitable number of UEs 110 and network nodes 120 and 130, as well as anyadditional elements suitable to support communication between UEs orbetween a UE and another communication device (such as a landlinetelephone). Furthermore, although certain embodiments may be describedas implemented in an LTE network, the embodiments may be implemented inany appropriate type of telecommunication system supporting any suitablecommunication standards (including 5G standards) and using any suitablecomponents, and are applicable to any RAT or multi-RAT systems in whicha UE receives and/or transmits signals (e.g., data). For example, thevarious embodiments described herein may be applicable to LTE,LTE-Advanced, 5G, NR, UMTS, HSPA, GSM, cdma2000, WCDMA, WiMax, UMB,WiFi, another suitable radio access technology, or any suitablecombination of one or more RATs.

1 MULTIPLE SCTP ASSOCIATIONS PER S1AP CONNECTION 1.1 New Requirement onAdditional SCTP Associations

As discussed above, existing 3GPP specifications only define one singleSCTP association per MME and eNB pair. As a result, problems can arise,for example, because all UEs supported by the single SCTP associationmay lose connectivity to the network if a failure occurs on the singleSCTP association. To address this problem, certain embodiments of thepresent disclosure introduce a new requirement to provide additionalSCTP associations between the MME and eNB. FIGS. 11-12 illustrateexamples of mapping S1 signaling to multiple SCTP connections.

There are several possibilities to map S1 signaling to multiple SCTPconnections. However, as an example, a distinction can be made betweennon-UE associated S1AP procedures and UE associated S1AP procedures.

FIG. 11 illustrates a first example of mapping in which all the SCTPassociations mapped to a single S1AP connection are setup in a way thatthey may carry both non UE-associated signaling procedures andUE-associated signaling. In certain embodiments, certain nonUE-associated signaling uses only one of the SCTP associations at atime. That is, one SCTP association for non-UE associated signalingwould be in use while the other SCTP association(s) for non-UEassociated signaling would be idle. In other embodiments, specificnon-UE associated signaling will be sent on an “idle” SCTP association.

FIG. 12 illustrates a second example of mapping of non UE-associatedprocedures and UE-associated procedures. One SCTP connection could carrynon-UE associated signaling procedures and other SCTP connections couldcarry UE-associated signaling procedures. This arrangement of S1APsignaling split is beneficial to guarantee that at least one SCTPconnection remains active to carry essential procedures like Paging,while other SCTP procedures may be suspended or removed.

For the first mapping example described above (FIG. 11), one proposedsolution provides for the following conditions on SCTP associationsestablished between one MME and eNB pair:

-   -   For each SCTP association, a single pair of stream identifiers        shall be reserved for the sole use of S1AP elementary procedures        that utilize non UE-associated signaling.    -   For each SCTP association, at least one pair of stream        identifiers shall be reserved for the sole use of S1AP        elementary procedures that utilize UE-associated signaling.        However a few pairs (i.e., more than one) should be reserved.    -   Non UE-associated signaling shall be transmitted on only one of        the active SCTP associations, and should not be changed unless a        controlled switching of SCTP instance is performed. Exceptions        apply in connection to SCTP association addition (and deletion)        to an existing S1AP.    -   A single UE-associated signaling shall use one SCTP stream on        any active SCTP associations, and the stream should not be        changed during the communication of the UE-associated signaling,        unless a controlled switching of SCTP association is performed.

For the second mapping example described above (FIG. 12), one proposedsolution could involve the following conditions on SCTP associationsestablished between one MME and eNB pair:

-   -   In at least one dedicated SCTP association, where a single pair        of stream identifiers shall be reserved for the sole use of S1AP        elementary procedures that utilize non UE-associated signaling.    -   In at least one dedicated SCTP association, where at least one        pair of stream identifiers shall be reserved for the sole use of        S1AP elementary procedures that utilize UE-associated        signalings. However a few pairs (i.e., more than one) should be        reserved.    -   Non UE-associated signaling and UE-associated signaling shall be        transmitted on separate SCTP associations.    -   Non UE-associated signaling shall be transmitted on only one        SCTP associations, and should not be changed unless a controlled        switching of SCTP instance is performed. Exceptions apply in        connection to SCTP association addition (and deletion) to an        existing S1AP.    -   A single UE-associated signaling shall use one SCTP stream on        any active SCTP associations, and the stream should not be        changed during the communication of the UE-associated signaling,        unless a controlled switching of SCTP association is performed.

1.2 Identification for Mapping of Individual SCTP Association to S1AP

In certain embodiments, several SCTP associations may be dynamicallyattached and detached from the S1AP instance. Thus, there is a need foridentification and mapping of SCTP association to the S1AP context onboth endpoints. For each SCTP association and S1AP signaling bundlerunning over it, a single S1AP identifier may be assigned. Suchidentifier identifies the portion of the S1 signaling connection betweeneNB and MME running on the specific SCTP connection. In one embodimentof this proposed solution, the identifier could be made of a common part(e.g., made of a number of left most bits) identifying the overalleNB-MME S1 signaling connection, plus a specific part (e.g., made of anumber of right most bits) that identifies the S1AP signaling bundleongoing on the specific SCTP connection in question. In the exampleabove such configuration would assign a separate SCTP connection for theS1AP signaling bundle carrying non-UE associated procedures and one ormore separate SCTP connections for the S1AP signaling bundles carryingUE-associated procedures. Each S1AP signaling bundle is assigned aunique identifier and all procedures related to one UE will be keptwithin the same SCTP connection.

FIG. 13 illustrates an example assignment of S1AP identifiers todistinguish between main S1AP signaling connection and S1 signalingbundles on different SCTP instances. In the example embodiment depictedin Error! Reference source not found. FIG. 13, the S1 signalingconnection established between the eNB and the MME is split into anumber of sub bundles. Each sub bundle carries part of the signaling forthe overall signaling connection. Each sub bundle is associated to aseparate SCTP connection. In the example explained above one sub bundleis in charge of carrying non-UE associated signaling, while one or moresub bundles are in charge of carrying UE associated signaling.

FIG. 13 provides a further example in which the S1 signaling connectionis assigned an identifier, named S1 Configuration ID and assumed to be Xbits long, that is unique between eNB and MME. Such identifieridentifies the specific configurations for the S1 connection. Forexample, such identifier is able to identify a context for the signalingconnection in which are stored details like Tracking Area Codes (TACs)and PLMN IDs supported by the eNB; PLMN IDs, MME Group IDs and MME Codes(MMECs) served by the MME. Each S1AP bundle, i.e., signaling portion ofthe main S1 signaling connection, may be identified by a parameter thatis herein named S1 Signaling Bundle ID and that is made of the S1Configuration ID (X bits) plus a Bundle ID (y bits). The bundle ID isunique within the eNB and MME pair.

For assigning bundle ID to the endpoints, one example method (i.e.,“method 1”) exchanges additional identifiers during S1 setup procedure,and during SCTP association addition procedure. After the procedure iscompleted, the initial/added SCTP association is assigned a unique S1Signaling Bundle ID, and this mapping information is stored in the S1APcontext on both endpoints.

For example, during S1 Setup procedure, in S1 SETUP REQUEST, eNBprovides two (for eNB) unique identifiers to MME. One identifier for theS1AP instance “eNB S1 Configuration ID” and one identifier for the SCTPassociation “eNB S1 Signaling Bundle ID”. In S1 SETUP RESPONSE, MMEprovides two corresponding unique (for MME) identifiers to MME, “MME S1Configuration ID” and “MME S1 Signaling Bundle ID” to eNB. TheseS1AP/SCTP association identities are stored in S1AP context in bothsides after the S1 setup and/or S1 association addition procedure iscompleted. By these identifiers, both endpoints may then be able toselect the correct SCTP instance in S1AP context for e.g., deletion ofSCTP instance. An example of these additional parameters, with MME S1Configuration ID, MME S1 Signaling Bundle ID, eNB S1 Configuration IDand eNB S1 Signaling Bundle ID, with value range between 1 and 2³²−1,can be found in Table 1 and Table 2 below.

TABLE 1 S1 SETUP REQUEST with eNB S1 Configuration ID and eNB S1Signaling Bundle ID. IE/Group IE type and Assigned Name Presence Rangereference Semantics Criticality Criticality Message Type M 9.2.1.1 YESreject Global eNB ID M 9.2.1.37 YES reject eNB Name OPrintableString(SIZE YES ignore (1 . . . 150, . . .)) Supported TAs 1 .. . Supported TAs in GLOBAL reject <maxnoofTACs> the eNB. >TAC M 9.2.3.7Broadcast TAC. — >Broadcast 1 . . . Broadcast PLMNs. — PLMNs<maxnoofBPLMNs> >>PLMN M 9.2.3.8 Identity Default Paging M 9.2.1.16 YESignore DRX CSG Id List 0 . . . 1 GLOBAL reject >CSG Id 1 . . . 9.2.1.62<maxnoofCSGIds> eNB S1 O 1 . . . 2³² − 1 eNB S1 ConfigurationConfiguration ID ID for re-establishment eNB S1 O 1 . . . 2³² − 1 eNBSCTP Signaling association ID for Bundle ID the S1AP instance

TABLE 2 S1 SETUP RESPONSE with MME S1 Configuration ID and MME S1Signaling Bundle ID IE/Group IE type and Assigned Name Presence Rangereference Semantics Criticality Criticality Message Type M 9.2.1.1 YESreject MME Name O PrintableString(SIZE YES ignore (1 . . . 150, . . .))Served 1 . . . The LTE related pool GLOBAL reject GUMMEIs <maxnoofRATs>configuration is included on the first place in the list. >Served 1 . .. — PLMNs <maxnoofPLMNsPerMME> >>PLMN M 9.2.3.8 — Identity >Served 1 . .. — GroupIDs <maxnoofGroupIDs> >>MME M OCTET STRING — Group ID(SIZE(2)) >Served 1 . . . — MMECs <maxnoofMMECs> >>MME M 9.2.3.12 — CodeRelative MME M 9.2.3.17 YES ignore Capacity MME Relay O 9.2.1.82 YESignore Support Indicator Criticality O 9.2.1.21 YES Ignore DiagnosticsMME S1 O 1 . . . 2³² − 1 MME S1AP Configuration ID Configuration ID forre-establishment MME S1 O 1 . . . 2³² − 1 MME SCTP Signaling associationID for Bundle ID the S1AP instance

For backward compatibility, the eNB may omit eNB SCTP S1AP ID in S1SETUP REQUEST signal if it has no multiple SCTP association capability.MME may ignore eNB SCTP S1AP ID if it is a legacy node or it has nomultiple SCTP association capability, and MME returns S1 SETUP RESPONSEwithout MME SCTP S1AP ID to inform eNB its lack of capability.

Another example method (i.e., “method 2”) for assigning bundle ID to theendpoints only assigns the identifier during S1 Setup and S1 signalingbundle addition procedure, and mapping between SCTP association and thesignaling bundle ID is done first when the S1AP signal is transmittedthrough the SCTP. In this example method, the identifiers may beassigned according to the scheme shown in FIG. 12. Table 3 shows howsuch identifiers may be used in the current message structure.

TABLE 3 S1 SETUP REQUEST with S1 signaling Connection IDs. IE/Group IEtype and Assigned Name Presence Range reference Semantics CriticalityCriticality Message Type M 9.2.1.1 YES reject Global eNB ID M 9.2.1.37YES reject eNB Name O PrintableString(SIZE YES ignore (1 . . . 150, . ..)) Supported TAs 1 . . . Supported TAs in GLOBAL reject <maxnoofTACs>the eNB. >TAC M 9.2.3.7 Broadcast TAC. — >Broadcast PLMNs 1 . . .Broadcast PLMNs. — <maxnoofBPLMNs> >>PLMN M 9.2.3.8 Identity DefaultPaging M 9.2.1.16 YES ignore DRX CSG Id List 0 . . . 1 GLOBALreject >CSG Id 1 . . . 9.2.1.62 <maxnoofCSGIds> S1 Configuration OEnumerated(0 . . . 127) Identifier for ID the S1 signaling configurationS1 Bundle List O 0 . . . 1 List of signaling bundles forming the S1signaling connection >S1 Signaling 1 . . . Bundles<maxnoofS1SignalingBundles> >> S1 Signaling M Enumerated(0 . . . 255)Identifier for each Bundle ID signaling bundle forming the S1 signalingconnection between eNB and MME. The X leftmost bits consist of the S1Configuration ID IE

In this example, the S1 SETUP REQUEST eNB will provide S1 SignalingBundle ID for all the SCTP associations which will be mapped to the S1APconnection. In the S1 SETUP RESPONSE the MME may reply by adding anoptional flag with value “supported” or “not supported” that specifieswhether the received new IDs in the S1 SETUP REQUEST are supported andcorrectly received. If the flag is set to “not supported” or it ismissing, the MME has no support for sub bundling of the S1 signalingconnection and the eNB should fold back to legacy S1 connectionconfiguration, namely to a scheme where the S1 signaling connection ismapped to only one SCTP connection.

As part of this example embodiment, an S1 Signaling Bundle ID may beadded to each S1 signaling message or to some of them. When a S1APmessage is transmitted through any of the related SCTP association afterS1 Setup procedure has been executed, this S1 Signaling Bundle ID willbe used in order to identify the signaling bundle to which the messagebelongs, and which bundle ID this SCTP association is mapped to theS1AP. As part of the embodiment some or all S1 signaling messages mayinclude also the S1 configuration ID, to identify the S1 signalingcontext to which the messages belong, and to which S1AP the messagecarrying SCTP association belongs.

In an alternative embodiment of the proposed solution, the S1 SignalingBundle IDs may be omitted and only the S1 Configuration ID may be used,after the initial UE associated procedure has been executed. Thisexample embodiment assumes that the UE-associated signaling for a UE issent all within the same SCTP connection. The embodiment provides thatthe MME UE S1AP ID and eNB UE S1AP ID included in each UE associated S1signaling message may identify the association between the UE associatedsignaling and the SCTP connection used by such signaling.

These example embodiments may also be applied to the X2 interface. Forthe X2 interface, the S1 Configuration ID and S1 Signaling Bundle ID maybe named X2 Configuration ID and X2 Signaling Bundle ID, while the UEIDs that may be used in replacement for the X2 Signaling Bundle ID arethe MME UE X2AP ID and eNB UE X2AP ID. The embodiments for the X2interface foresee, as per the S1 interface, that the X2 interfacesignaling may be distributed over multiple SCTP connections.

1.3 Adding, (Gracefully) Deleting, and Handling of Broken SCTPAssociation to Existing S1AP 1.3.1 Adding SCTP Association

In case of method 1 for assigning S1 Signaling Bundle ID to theendpoints, the adding procedure applies when S1AP wants to add a newSCTP association. An example on sequence diagram for addition is shownin FIG. 14 (i.e., add SCTP association to existing S1AP for method 1).

In step 1 of FIG. 14, in case MME wants to add a SCTP association toS1AP, it transmits a non UE-associated S1AP message “S1 BUNDLE ADDITIONREQUIRED” to eNB. An optional parameter “Transport Network (TN) address”may be added in the message if MME wants eNB to establish SCTP in aspecific MME interface.

In steps 2-5 of FIG. 14, in case eNB wants to add a SCTP association toS1AP, or after receiving “S1 BUNDLE ADDITION REQUIRED” from MME, eNBwill establish a new SCTP association towards MME according to currentstandard. The new SCTP association may be distinct from the existingSCTP associations by e.g., different eNB IP address, different eNB IPport, different MME IP address etc.

In step 6 of FIG. 14, after the new SCTP association has beenestablished between eNB and MME, eNB will map this SCTP association tothe corresponding S1AP instance, assign a new identity “eNB S1 SignalingBundle ID” to the new SCTP association, and transmit a non UE-associatedS1AP message S1 BUNDLE ADDITION REQUEST through this newly establishedSCTP association and on the stream dedicated for non UE-associatedsignaling. In this message, parameter “MME S1 Config ID” has beenreceived from S1 SETUP procedure earlier and parameter “eNB S1 SignalingBundle ID” is the new identity mentioned earlier in this step.

In step 7 of FIG. 14, after S1 BUNDLE ADDITION REQUEST has beenreceived, MME will map the SCTP association with the correct S1APinstance according to parameter “MME S1 Config ID”, store “eNB S1Signaling Bundle ID” to the S1AP instance for identifying this new SCTPassociation, assign a new identity “MME S1 Signaling Bundle ID” to thenew SCTP association, and transmit a non UE-associated S1AP message S1BUNDLE ADDITION CONFIRM through this newly established SCTP associationand on the stream dedicated for non UE-associated signaling. In thismessage, parameter “eNB S1 Configuration ID” has been received from S1SETUP procedure earlier, and parameter “MME S1 Signaling Bundle ID” isthe new identity mentioned earlier in this step.

After S1 BUNDLE ADDITION CONFIRM has been received, eNB will store “MMES1 Signaling Bundle ID” to the S1AP instance for identifying this newSCTP association. UE associated signaling may from now on be assigned tothe streams in this new SCTP association.

In case of method 2 for assigning S1 Signaling Bundle ID to theendpoints, the adding procedure applies when additional bundle ID isneeded besides those bundle IDs which are defined during S1 SETUPprocedure. FIG. 15 shows the sequence diagram when this addition isinitiated by MME (i.e., add SCTP association to existing S1AP for method2, MME initiated).

In step 1 of FIG. 15, in case MME wants to add a SCTP association toS1AP, it transmits a non UE-associated S1AP message “S1 BUNDLE ADDITIONREQUEST” to eNB. This message includes a list of S1 Signaling Bundle ID,which identifies the signaling bundle over the new SCTP associations tobe established, an optional parameter “TN address” may be added for eachelement in the list if MME wants eNB to establish SCTP in a specific MMEinterface.

In steps 2-5 of FIG. 15, after receiving “S1 BUNDLE ADDITION REQUEST”from MME, eNB will establish new SCTP associations towards MME accordingto current standard. The new SCTP association may be distinct from theexisting SCTP associations by e.g., different eNB IP address, differenteNB IP port, different MME IP address etc. The SCTP associationsestablishment may be executed in parallel with step 6 below.

In step 6 of FIG. 15, after receiving “S1 BUNDLE ADDITION REQUEST” fromMME, eNB will store the list of “S1 Signaling Bundle ID″s, and transmita non UE-associated S1AP message S1 BUNDLE ADDITION CONFIRM.

FIG. 16 shows the sequence diagram when this addition is initiated byeNB (i.e., add SCTP association to existing S1AP for method 2, eNBinitiated).

In steps 1-4 of FIG. 16, eNB establishes new SCTP associations towardsMME according to current standard. The new SCTP association may bedistinct from the existing SCTP associations by e.g., different eNB IPaddress, different eNB IP port, different MME IP address etc. The SCTPassociations establishment may be executed in parallel with step 5below.

In step 5 of FIG. 16, in case eNB wants to add a SCTP association toS1AP, it may transmit a non UE-associated S1AP message “S1 BUNDLEADDITION REQUEST” to MME. This message includes a list of S1 SignalingBundle ID, which identifies the signaling bundle over the new SCTPassociations to be established.

In step 6 of FIG. 16, after receiving “S1 BUNDLE ADDITION REQUEST” fromeNB, MME will store the list of “S1 Signaling Bundle ID”s, and transmita non UE-associated S1AP message S1 BUNDLE ADDITION CONFIRM.

For method 2 for assigning S1 Signaling Bundle ID to the endpoints, aspart of this embodiment an S1 Signaling Bundle ID may be added to eachS1 signaling message or to some of them. When a S1AP message istransmitted through any of the related SCTP association after S1 Setupprocedure has been executed, this S1 Signaling Bundle ID will be used inorder to identify the signaling bundle to which the message belongs, andwhich bundle ID this SCTP association is mapped to the S1AP. As part ofthe embodiment some or all S1 signaling messages may include also the S1configuration ID, to identify the S1 signaling context to which themessages belong, and which S1AP the message carrying SCTP associationbelongs to.

For all examples for mapping of S1 signaling, and all methods forassigning S1 Signaling Bundle ID to the endpoints, the procedure aboveallows to add SCTP connections for the purpose of redistributing S1APsignaling traffic. The procedure may also be applied to the X2interface.

1.3.2 (Gracefully) Deleting SCTP Association

In case of method 1 for assigning S1 Signaling Bundle ID to theendpoints, an example sequence diagram for graceful deletion of existingSCTP association which is carrying non UE-associated signaling from S1APis shown in FIG. 17 (graceful deletion of SCTP association carryingnon-UE associated signaling from S1AP for method 1).

In step 1 of FIG. 17, in case MME wants to delete an existing SCTPassociation from S1AP, it transmits a non UE-associated S1AP message “S1BUNDLE DELETION REQUIRED” to eNB. This message may either be transmittedthrough the SCTP association which should be deleted (not shown in thefigure), or through the SCTP association assigned for non UE-associatedsignaling (shown in the figure). In case of the latter case, an extraparameter “eNB S1 Signaling Bundle ID” is provided for pointing outwhich SCTP association should be deleted.

In step 2 of FIG. 17, in case eNB wants to delete a SCTP associationfrom S1AP, or after receiving “S1 BUNDLE DELETION REQUIRED” from MME,eNB will stop all outgoing non UE-associated signaling and all outgoingUE-associated signaling if applicable, which are assigned to thedeleting SCTP association by informing the higher layer.

In step 3 of FIG. 17, after all related outgoing signaling has beenstopped from eNB, eNB will transmit “S1 BUNDLE DELETION REQUEST” to MME.This message may either be transmitted through the SCTP associationwhich should be deleted (not shown in the figure), or through the SCTPassociation assigned for non UE-associated signaling (shown in thefigure). In case of the latter case, an extra parameter “MME S1Signaling Bundle ID” is needed for pointing out which SCTP associationshould be deleted.

In step 4 of FIG. 17, after receiving “S1 BUNDLE DELETION REQUEST” fromeNB, MME will stop all outgoing non UE-associated signaling and alloutgoing UE-associated signaling if applicable, which are assigned tothe deleting SCTP association by informing the higher layer.

In step 5 of FIG. 17, after all related outgoing signaling has beenstopped from MME, MME will transmit “S1 BUNDLE DELETION CONFIRM” to eNB.This message may either be transmitted through the SCTP associationwhich should be deleted (not shown in the figure), or through the SCTPassociation assigned for non UE-associated signaling (shown in thefigure). In case of the latter case, an extra parameter “eNB S1Signaling Bundle ID” is needed for pointing out which SCTP associationshould be deleted.

In steps 6-8 of FIG. 17, after receiving “S1 BUNDLE DELETE CONFIRM” fromMME, eNB will initiate SCTP closure of the SCTP association according tocurrent standard. As all non UE-associated and eventually UE-associatedconnections have been stopped for the SCTP association, S1AP packetdelivery can be guaranteed.

In step 9 of FIG. 17, after receiving SHUTDOWN-ACK from the deletingSCTP association, eNB will transmit message S1 NON UE-ASSOCIATEDRE-ESTABLISH REQUEST to MME through one of the remaining SCTPassociation which eNB assigns it for non UE associated signaling.

In step 10 of FIG. 17, after receiving S1 NON UE-ASSOCIATED RE-ESTABLISHREQUEST, MME maps the non UE associated signaling to the SCTPassociation where the message come from, and transmit S1 NONUE-ASSOCIATED RE-ESTABLISH CONFIRM through the same SCTP association.

In step 11 of FIG. 17, after transmitting S1 NON UE-ASSOCIATEDRE-ESTABLISH CONFIRM, MME informs higher layer that non UE-associatedsignaling may be resumed, and all the outgoing signals will be directedto the new SCTP association.

In step 12 of FIG. 17, after receiving S1 NON UE-ASSOCIATED RE-ESTABLISHCONFIRM, eNB informs higher layer that non UE-associated signaling maybe resumed, and all the outgoing signals will be directed to the newSCTP association.

An example sequence diagram for graceful deletion of existing SCTPassociation which is carrying UE-associated signaling from S1AP formethod 1 is shown in FIG. 18 (graceful deletion of SCTP associationcarrying UE associated signaling from S1AP for method 1). Error!Reference source not found.

In step 1 of FIG. 18, In case MME wants to delete an existing SCTPassociation from S1AP, it transmits a non UE-associated S1AP message “S1BUNDLE DELETION REQUIRED” to eNB. This message may either be transmittedthrough the SCTP association which should be deleted (not shown in thefigure), or through the SCTP association assigned for non UE-associatedsignaling (shown in the figure). In case of the latter case, an extraparameter “eNB S1 Signaling Bundle ID” is provided for pointing outwhich SCTP association should be deleted.

In step 2 of FIG. 18, in case eNB wants to delete a SCTP associationfrom S1AP, or after receiving “S1 BUNDLE DELETION REQUIRED” from MME,eNB will stop all outgoing UE-associated signaling and all outgoing nonUE-associated signaling if applicable, which are assigned to thedeleting SCTP association by informing the higher layer.

In step 3 of FIG. 18, after all related outgoing signaling has beenstopped from eNB, eNB transmits “S1 BUNDLE DELETION REQUEST” to MME.This message may either be transmitted through the SCTP associationwhich should be deleted (not shown in the figure), or through the SCTPassociation assigned for non UE-associated signaling (shown in thefigure). In case of the latter case, an extra parameter “MME S1Signaling Bundle ID” is provided for pointing out which SCTP associationshould be deleted.

In step 4 of FIG. 18, after receiving “S1 BUNDLE DELETION REQUEST” fromeNB, MME stops all outgoing UE-associated signaling and all outgoing nonUE-associated signaling if applicable, which are assigned to thedeleting SCTP association by informing the higher layer.

In step 5 of FIG. 18, after all related outgoing signaling has beenstopped from MME, MME transmits “S1 BUNDLE DELETION CONFIRM” to eNB.This message may either be transmitted through the SCTP associationwhich should be deleted (not shown in the figure), or through the SCTPassociation assigned for non UE-associated signaling (shown in thefigure). In case of the latter case, an extra parameter “eNB S1Signaling Bundle ID” is provided for pointing out which SCTP associationshould be deleted.

In steps 6-8 of FIG. 18, after receiving “S1 BUNDLE DELETE CONFIRM” fromMME, eNB initiates SCTP closure of the SCTP association according tocurrent standard. As all non UE-associated and eventually UE-associatedconnections have been stopped for the SCTP association, S1AP packetdelivery can be guaranteed.

In step 9 of FIG. 18, after receiving SHUTDOWN-ACK from the deletingSCTP association, and if there are any S1AP UE associated signaling wasassigned to the deleted SCTP association, eNB maps the UE association tothe remaining SCTP associations, and transmits message S1 UE-ASSOCIATEDRE-ESTABLISH REQUEST to MME with the new mapping. This signal istransmitted with one of the follow alternatives:

-   -   a) (As shown in the figure) Through SCTP association assigned        for non UE-associated signaling, in this case this message is a        non UE-associated signal. Parameter consisting of mapping        between eNB UE S1AP ID/MME UE S1AP ID and MME S1 Signaling        Bundle ID is provided for each UE association. This signal may        be sent per UE association, or for all UE associations which        need re-establishment.    -   b) (Not shown in the figure) Through SCTP association where the        UE associated signaling will be re-established as a non        UE-associated signal. Parameter consisting of a list of eNB UE        S1AP ID/MME UE S1AP ID is provided.    -   c) (Not shown in the figure) Through SCTP association where the        UE associated signaling will be re-established as a        UE-associated signal. Parameter consisting of eNB UE S1AP ID/MME        UE S1AP ID is provided.

In step 10 of FIG. 18, after receiving S1 UE-ASSOCIATED RE-ESTABLISHREQUEST, MME maps the corresponding UE association to the new SCTPassociation, and transmits S1 UE-ASSOCIATED RE-ESTABLISH CONFIRM withthe same alternative according to previous step.

In step 11 of FIG. 18, MME informs higher layer that the correspondingUE-associated signaling may be resumed, and all the outgoing signalswill be directed to the new SCTP association.

In step 12 of FIG. 18, after receiving S1 UE-ASSOCIATED RE-ESTABLISHCONFIRM, eNB informs higher layer that the corresponding UE-associatedsignaling may be resumed, and all the outgoing signals will be directedto the new SCTP association.

In case of method 2 for assigning S1 Signaling Bundle ID to theendpoints, an example on sequence diagram for graceful deletion ofexisting SCTP association initiated by MME is shown in FIG. 19 (gracefuldeletion of SCTP association from S1AP initiated by MME for method 2).

In step 1 of FIG. 19, in case MME wants to delete one or several SCTPassociation from S1AP, MME stops all outgoing UE-associated signalingand all outgoing non UE-associated signaling, which are assigned to thedeleting SCTP associations by informing the higher layer.

In step 2 of FIG. 19, after all related outgoing signaling has beenstopped from MME, MME transmits “S1 BUNDLE DELETION REQUEST” to eNBthrough the SCTP association assigned for non UE-associated signalingwith parameter consists of a list of “S1 Signaling Bundle ID” pointingout which SCTP associations should be deleted. MME will also start MMES1 Bundle deletion timer (2a)

In step 3 of FIG. 19, after receiving “S1 BUNDLE DELETION REQUEST” fromMME, eNB stops all outgoing UE-associated signaling and all outgoing nonUE-associated signaling, which are assigned to the deleting SCTPassociations by informing the higher layer. eNB also starts eNB S1Bundle deletion timer (3a).

In steps 4-6 of FIG. 19, after stopping all related S1AP signaling, eNBinitiates SCTP closure of the SCTP association according to currentstandard. As all non UE-associated and eventually UE-associatedconnections have been stopped for the SCTP association, S1AP packetdelivery can be guaranteed. When eNB receives SHUTDOWN-ACK it stops theeNB S1 Bundle deletion timer, and when MME receives SHUTDOWN-COMPLETE itstops the MME S1 Bundle deletion timer.

An example on sequence diagram for graceful deletion of existing SCTPassociation from S1AP initiated by eNB for method 2 is shown in FIG. 20(graceful deletion of SCTP association from S1AP initiated by eNB formethod 2).

In step 1 of FIG. 20, in case eNB wants to delete one or several SCTPassociation from S1AP, eNB stops all outgoing UE-associated signalingand all outgoing non UE-associated signaling, which are assigned to thedeleting SCTP associations by informing the higher layer.

In step 2 of FIG. 20, after all related outgoing signaling has beenstopped from eNB, eNB transmits “S1 BUNDLE DELETION REQUEST” to MMEthrough the SCTP association assigned for non UE-associated signalingwith parameter consists of a list of “S1 Signaling Bundle ID” pointingout which SCTP associations should be deleted. eNB will also start eNBS1 Bundle deletion timer (2a).

In step 3 of FIG. 20, after receiving “S1 BUNDLE DELETION REQUEST” fromeNB, MME stops all outgoing UE-associated signaling and all outgoing nonUE-associated signaling, which are assigned to the deleting SCTPassociations by informing the higher layer. MME also starts MME S1Bundle deletion timer (3a).

In steps 4-6 of FIG. 20, after stopping all related S1AP signaling, MMEinitiates SCTP closure of the SCTP association according to currentstandard. As all non UE-associated and eventually UE-associatedconnections have been stopped for the SCTP association, S1AP packetdelivery can be guaranteed. When MME receives SHUTDOWN-ACK it stops theMME S1 Bundle deletion timer, and when eNB receives SHUTDOWN-COMPLETE itstops the eNB S1 Bundle deletion timer.

In case of method 2 for assigning S1 Signaling Bundle ID to theendpoints, mapping to new SCTP connections of procedures for which theSCTP connection has been removed is achieved by simply triggering suchprocedures and adding to the procedures messages the S1 ConnectionBundle ID, and optionally, the S1 Configuration ID. This mechanismallows the receiving node to understand that signaling for the affectedprocedure shall be mapped to the SCTP connection corresponding to the S1Connection Bundle ID flagged. Also, the receiver may deduce that mappingof non-UE associated signaling procedures to a specific SCTP connection,or mapping of UE associated signaling for a specific UE to a given SCTPconnection, by analyzing the S1 Connection Bundle ID of the firstsignaling message received (of the UE associated or non UE associatednature) and based on the analysis, may assume that remaining signalingwill be sent over the identified SCTP connection.

1.3.3 Handling of Broken SCTP Association

An example of a sequence diagram for handling of broken SCTP associationwhere non UE-associated signaling is not assigned is shown in FIG. 21(broken SCTP association handling to existing S1AP). FIG. 21 shows anexample modification of existing RESET and RESET ACKNOWLEDGE, by adding“MME S1 Signaling Bundle ID”, “eNB S1 Signaling Bundle ID” parameters tothe messages. In an alternative example modification, of existing RESET,the parameters S1 Connection Bundle ID and optionally the S1 Context ID(not shown in the figure) are added to the messages.

In case of an endpoint which detects the SCTP association is broken,this endpoint should transmit RESET with parameter “<xx> S1 SignalingBundle ID” to the destination endpoint, where <xx> is the name of thedestination endpoint (shown in the figure). Alternatively, the endpointmay transmit RESET with parameter S1 Connection Bundle ID and optionallythe S1 Context ID (not shown in the figure).

After receiving RESET, the destination endpoint shall reply with RESETACKNOWLEDGE with parameter “<yy> S1 Signaling Bundle ID”, where <yy> isthe name of the originating endpoint (shown in the figure).Alternatively, the endpoint should transmit RESET with parameter S1Connection Bundle ID and optionally the S1 Context ID (not shown in thefigure).

All of the UE associations mapped to the broken SCTP association shallbe reset and handled as the current standard.

If the broken SCTP association is assigned for non UE-associatedsignaling, the entire S1AP shall be reset according to current standard.

2 MOVING S1AP SIGNALING CONNECTION BETWEEN SCTP ASSOCIATIONS

The above-described solutions allow for establishing multiple SCTPassociations on S1AP. Once multiple SCTP associations have beenestablished, S1AP signaling connections can be moved between SCTPassociations.

In a first example embodiment, eNB is always used as the initiatingendpoint, and explicitly provides the destination SCTP associationidentity (S1 connection bundle ID) during the moving procedure.

In a second example embodiment, both eNB and MME may be used as theinitiating endpoint, and implicitly provides the destination identityduring the moving procedure.

Examples of methods for moving non-UE associated signaling andUE-associated signaling are described separately below.

2.1 Moving UE-Associated Signaling Between SCTP Associations, SuccessfulCase, First Embodiment

A sequence diagram on how multiple UE-associated signaling connectionsare successfully moved between SCTP associations is shown in FIG. 22(move multiple UE-associated signaling connections between SCTPassociations, first embodiment, successful case).

In step 1 of FIG. 22, in case MME wants to move existing UE-associatedsignaling connections to another SCTP association, it may transmit anUE-associated S1AP message “S1 UE-ASSOCIATED MOVE REQUIRED” to eNB, witha list of “MME UE S1AP ID”, “eNB UE S1AP ID” as parameter foridentifying the UE-associated signaling connections, for each element inthe list, optional “eNB S1 connection bundle ID” may be added foridentifying which SCTP association each individual UE-associatedsignaling connection is moving to.

In step 2 of FIG. 22, in case eNB wants to move existing UE-associatedsignaling connections to another SCTP association, or after receiving“S1 UE-ASSOCIATED MOVE REQUIRED” from MME, eNB stops all outgoingsignaling from each UE-associated signaling connection by informing thehigher layer. It is possible that the eNB may deliver S1AP messages thatwere pending transmission, buffered on SCTP layer or below, before thedecision to move the signaling connection to a different SCTP instancewas taken.

In step 3 of FIG. 22, after all related outgoing signaling has beenstopped from eNB, for each individual UE-associated signalingconnection, eNB transmits a UE-associated signal “S1 UE-ASSOCIATED MOVEREQUEST” to MME. This message has the role of a “stop marker”, indicatesthe last message from eNB transmitted on the old SCTP association forthe specific UE-associated signaling connection identified by eNB S1APID and MME S1AP ID, before move. As this “stop marker” signal istransmitted after all pending S1AP messages, this “stop marker” messagewill be the last message received by the destination before the outgoingmessages is stopped for the signaling connection.

In step 4 of FIG. 22, after receiving “S1 UE-ASSOCIATED MOVE REQUEST”from eNB, MME stops all outgoing signaling from each UE-associatedsignaling connections by informing the higher layer. It is possible thatthe MME may deliver S1AP messages that were pending transmission,buffered on SCTP layer or below, before the decision to move thesignaling connection to a different SCTP instance was taken.

In step 5 of FIG. 22, after all related outgoing signaling has beenstopped from MME, for each individual UE-associated signalingconnection, MME transmits UE-associated signal “S1 UE-ASSOCIATED MOVECONFIRM” to eNB. This message has the role of a “stop marker”, indicatesthe last message from MME transmitted on the old SCTP association forthe specific UE-associated signaling connection identified by eNB S1APID and MME S1AP ID, before move. As this “stop marker” signal istransmitted after all pending S1AP messages, this “stop marker” messagewill be the last message received by the destination before the outgoingmessages is stopped for the signaling connection.

In step 6 of FIG. 22, after receiving S1 UE-ASSOCIATED MOVE CONFIRM overthe old SCTP association from all the involving UE-associated signalingconnections, eNB maps each UE-associated signaling connection to a newSCTP association either decided by eNB or by MME via parameter “eNB S1connection bundle ID” from step 1 if applicable, and transmit message S1UE-ASSOCIATED RE-ESTABLISH REQUEST to MME with the new mapping. Thissignal has a role of “start marker” and may be transmitted with one ofthe follow alternatives:

-   -   a) Transmits as non UE-associated signal(s) through the default        SCTP association assigned for non UE-associated signaling.        Mapping between eNB UE S1AP ID/MME UE S1AP ID and MME S1        Signaling Bundle ID is needed for each UE-associated signaling        connection. This signal may be sent per UE-associated signaling,        or for all UE-associated signalings which need re-establishment.    -   b) Transmits as non UE-associated signal(s) through each SCTP        associations where the UE associated signaling connections will        be re-established. This signal may be sent per UE-associated        signaling, or for all UE-associated signalings which need        re-establishment Parameter of the signal(s) consists of (a list        of) eNB UE S1AP ID/MME UE S1AP ID and S1 Signaling bundle ID.    -   c) Transmits as an UE-associated signal for each UE-associated        signaling connection through the SCTP association where the UE        associated signaling connection will be re-established.        Parameter consists of eNB UE S1AP ID/MME UE S1AP ID.        For purposes of example, FIG. 22 shows alternative (a) of step        6, while alternatives (b) and (c) are not shown in the figure.        However, alternative (b) or (c) could be used in other        embodiments.

In step 7 of FIG. 22, after receiving S1 UE-ASSOCIATED RE-ESTABLISHREQUEST, MME maps the corresponding UE-associated signaling connectionsto the new SCTP association, and transmit S1 UE-ASSOCIATED RE-ESTABLISHCONFIRM with the same alternative according to previous step.

In step 8 of FIG. 22, MME informs higher layer that the correspondingUE-associated signaling connections may be resumed, and all the outgoingsignals will be directed to the new SCTP association.

In step 9 of FIG. 22, after receiving S1 UE-ASSOCIATED RE-ESTABLISHCONFIRM, eNB informs higher layer that the corresponding UE-associatedsignaling connections may be resumed, and all the outgoing signals willbe directed to the new SCTP association.

2.2 Successful Case, Second Embodiment

Sequence diagrams on how a single UE-associated signaling connection issuccessfully moved between SCTP associations are shown in FIG. 23 (eNBinitiated) and FIG. 24 (MME initiated). That is, FIG. 23 illustratesmoving a single UE-associated signaling connection between SCTPassociations (second embodiment, successful case, eNB initiated), andFIG. 24 illustrates moving a single UE-associated signaling connectionbetween SCTP associations (second embodiment, successful case, MMEinitiated).

The below description is valid for both the eNB-initiated case (FIG. 23)and MME-initiated case (FIG. 24).

In step 1, if the originating node wants to move an existingUE-associated signaling connection to another SCTP association, it stopsall outgoing signaling from the UE-associated signaling connection byinforming the higher layer. It is possible that the originating node maydeliver S1AP messages that were pending transmission, buffered on SCTPlayer or below, before the decision to move the signaling connection toa different SCTP instance was taken.

In step 2, after all related outgoing signaling has been stopped fromthe originating node, it transmits a UE-associated signal “S1UE-ASSOCIATED MOVE REQUEST” through the old SCTP association to thedestination node. This message has the role of a “stop marker”,indicates the last message from the originating node transmitted on theold SCTP association for the specific UE-associated signaling connectionidentified by eNB S1AP ID and MME S1AP ID, before move. This stop markeralso provides new “S1 connection bundle ID” informing to which SCTPassociation this connection shall be moved to. As this “stop marker”signal is transmitted after all pending S1AP messages, this “stopmarker” message will be the last message received by the destinationnode before the outgoing messages is stopped for the signalingconnection.

In step 3, after receiving “S1 UE-ASSOCIATED MOVE REQUEST” from theoriginating node, the destination node stops all outgoing signaling fromthe UE-associated signaling connections by informing the higher layer.It is possible that the destination node may deliver S1AP messages thatwere pending transmission, buffered on SCTP layer or below, before thedecision to move the signaling connection to a different SCTP instancewas taken.

In step 4, after all related outgoing signaling has been stopped fromdestination node, it transmits UE-associated signal “S1 UE-ASSOCIATEDMOVE CONFIRM” through the old SCTP association to the originating node.This message has the role of a “stop marker”, indicates the last messagefrom MME transmitted on the old SCTP association for the specificUE-associated signaling connection identified by eNB S1AP ID and MMES1AP ID, before move. As this “stop marker” signal is transmitted afterall pending S1AP messages, this “stop marker” message will be the lastmessage received by the originating node before the outgoing messages isstopped for the signaling connection.

In step 5, after receiving S1 UE-ASSOCIATED MOVE CONFIRM, theoriginating node will inform higher layer that the correspondingUE-associated signaling connection may be resumed, and all the outgoingsignals will be directed to the new SCTP association. The firstUE-associated message over the new SCTP connection has a role of “startmarker” for the S1AP signaling connection.

In step 5a, in case there is no immediate UE-associated message fromhigher layer, the originating node transmits S1 UE-ASSOCIATED MOVECOMPLETE, with parameters eNB S1AP ID and MME S1AP ID, through the newSCTP association as the “start marker” (5a).

In step 6, after receiving a first UE-associated message or S1UE-ASSOCIATED MOVE COMPLETE from the new SCTP association, thedestination node informs higher layer that the correspondingUE-associated signaling connections may be resumed, and all the outgoingsignals will be directed to the new SCTP association.

An alternative procedure for decreasing the delay of moving is:

For the destination node, after transmitting UE-associated signal “S1UE-ASSOCIATED MOVE CONFIRM” through the old SCTP association (step 4),it will directly inform higher layer that the correspondingUE-associated signaling connection may be resumed (step 6), and all theoutgoing signals will be directed to the new SCTP association.

For the originating node, after transmitting UE-associated signal “S1UE-ASSOCIATED MOVE REQUEST” through the old SCTP association to thedestination node (step 2), if the originating node receives new messagesfrom the destination node through the new SCTP association, it will notforward these new messages to higher layer until “S1 UE-ASSOCIATED MOVECONFIRM” is received from the old SCTP association (step 4). Also inthis procedure eventual transmission of (step 5a) S1 UE-ASSOCIATED MOVECOMPLETE is omitted.

2.3 Error Case, All Embodiments

FIG. 25 shows an example of error case that can be used for both of theabove-described embodiments. In particular, FIG. 25 illustrates moving asingle UE-associated signaling between SCTP associations (failure case).Steps 1-3 are the same as discussed above with respect to the successfulcase (step 1 is omitted in the case of embodiment 2). In step 4, iferror occurs for some reason, e.g. invalid MME S1 connection bundle ID,MME will transmit “S1 UE ASSOCIATED MOVE REJECT” to eNB, informing thatthe move is aborted. In step 5, after receiving “S1 UE ASSOCIATED MOVEREJECT”, eNB will inform higher layer that the correspondingUE-associated signaling may be resumed, and all the outgoing signalswill continue through the original SCTP association.

2.4 Moving Non UE-Associated Signaling Between SCTP Associations,Successful Case, First Embodiment

A sequence diagram on how non UE-associated signaling is successfullymoved between SCTP associations is shown in FIG. 26 (moving nonUE-associated signaling between SCTP associations, successful case,first embodiment).

In step 1 of FIG. 26, in case MME wants to move the non UE-associatedsignaling to another SCTP association, it transmits a non UE-associatedS1AP message “S1 NON UE-ASSOCIATED MOVE REQUIRED” to eNB, with parameter“new eNB S1 Signaling Bundle ID” identifies the SCTP association the nonUE-associated signaling is moving to.

In step 2 of FIG. 26, in case eNB wants to move the non UE-associatedsignaling to another SCTP association, or after receiving “S1 NONUE-ASSOCIATED MOVE REQUIRED” from MME, eNB stops all outgoing signalingfrom the non UE-associated signaling connection by informing the higherlayer. It is possible that the eNB may deliver S1AP messages that werepending transmission, buffered on SCTP layer or below, before thedecision to move the signaling connection to a different SCTP instancewas taken.

In step 3 of FIG. 26, after all related outgoing signaling has beenstopped from eNB, eNB transmits a non UE-associated signal “S1 NONUE-ASSOCIATED MOVE REQUEST” to MME. This message has the role of a “stopmarker”, indicates the last message from eNB transmitted on the old SCTPassociation before move. As this “stop marker” signal is transmittedafter all pending S1AP messages, this “stop marker” message will be thelast message received by the destination before the outgoing messages isstopped for the signaling connection.

In step 4 of FIG. 26, after receiving “S1 NON UE-ASSOCIATED MOVEREQUEST” from eNB, MME stops all outgoing signaling from the nonUE-associated signaling connection by informing the higher layer. It ishowever possible that the MME may deliver S1AP messages that werepending transmission before the decision to move the signalingconnection to a different SCTP instance was taken.

In step 5 of FIG. 26, after all related outgoing signaling has beenstopped from MME, MME transmits non UE-associated signal “S1 NONUE-ASSOCIATED MOVE CONFIRM” to eNB. This message has the role of a “stopmarker”, indicates the last message from MME transmitted on the old SCTPassociation before move. As this “stop marker” signal is transmittedafter all pending S1AP messages, this “stop marker” message will be thelast message received by the destination before the outgoing messages isstopped for the signaling connection.

In step 6 of FIG. 26, after receiving S1 NON UE-ASSOCIATED MOVE CONFIRMover the old SCTP association, eNB maps the non UE-associated signalingconnection to a new SCTP association either decided by eNB or by MME viaparameter “eNB S1 connection bundle ID” from step 1 if applicable, andtransmit message S1 NON UE-ASSOCIATED RE-ESTABLISH REQUEST to MMEthrough the new SCTP association. This signal has a role of “startmarker” for the non UE-associated signaling connection.

In step 7 of FIG. 26, after receiving S1 NON UE-ASSOCIATED RE-ESTABLISHREQUEST, MME maps the non UE-associated signaling connection to the newSCTP association, and transmits S1 NON UE-ASSOCIATED RE-ESTABLISHCONFIRM through the new SCTP association.

In step 8 of FIG. 26, MME informs higher layer that the nonUE-associated signaling connection may be resumed, and all the outgoingsignals will be directed to the new SCTP association.

In step 9 of FIG. 26, after receiving S1 NON UE-ASSOCIATED RE-ESTABLISHCONFIRM, eNB informs higher layer that the non UE-associated signalingconnection may be resumed, and all the outgoing signals will be directedto the new SCTP association.

2.5 Successful Case, Second Embodiment

Sequence diagrams on how the non UE-associated signaling connection issuccessfully moved between SCTP associations are shown in FIG. 27 (eNBinitiated) and FIG. 28 (MME initiated). That is, FIG. 27 illustratesmoving a non UE-associated signaling connection between SCTPassociations (second embodiment, successful case, eNB initiated). FIG.28 illustrates moving a non UE-associated signaling connection betweenSCTP associations (second embodiment, successful case, MME initiated).

The below description is valid for both eNB initiated case and MMEinitiated case.

In step 1, if the originating node wants to move the non UE-associatedsignaling connection to another SCTP association, it stops all outgoingsignaling from the non UE-associated signaling connection by informingthe higher layer. It is possible that the originating node may deliverS1AP messages that were pending transmission, buffered on SCTP layer orbelow, before the decision to move the signaling connection to adifferent SCTP instance was taken.

In step 2, after all related outgoing signaling has been stopped fromthe originating node, it transmits a non UE-associated signal “S1 NONUE-ASSOCIATED MOVE REQUEST” through the old SCTP association to thedestination node. This message has the role of a “stop marker”,indicates the last message from the originating node transmitted on theold SCTP association for the non UE-associated signaling connectionbefore move. This stop marker also provides new “S1 connection bundleID” informing to which SCTP association this connection shall be movedto. As this “stop marker” signal is transmitted after all pending S1APmessages, this “stop marker” message will be the last message receivedby the destination node before the outgoing messages is stopped for thesignaling connection.

In step 3, after receiving “S1 NON UE-ASSOCIATED MOVE REQUEST” from theoriginating node, the destination node stops all outgoing signaling fromthe non UE-associated signaling connections by informing the higherlayer. It is possible that the destination node may deliver S1APmessages that were pending transmission, buffered on

SCTP layer or below, before the decision to move the signalingconnection to a different SCTP instance was taken.

In step 4, after all related outgoing signaling has been stopped fromdestination node, it transmits non UE-associated signal “S1 NONUE-ASSOCIATED MOVE CONFIRM” through the old SCTP association to theoriginating node. This message has the role of a “stop marker”,indicates the last message from MME transmitted on the old SCTPassociation for the non UE-associated signaling connection before move.As this “stop marker” signal is transmitted after all pending S1APmessages, this “stop marker” message will be the last message receivedby the originating node before the outgoing messages is stopped for thesignaling connection.

In step 5, After receiving S1 NON UE-ASSOCIATED MOVE CONFIRM, theoriginating node informs higher layer that the non UE-associatedsignaling connection may be resumed, and all the outgoing signals willbe directed to the new SCTP association. The first non UE-associatedmessage over the new SCTP connection has a role of “start marker” forthe S1AP signaling connection.

In step 5a, in case there is no immediate non UE-associated message fromhigher layer, the originating node transmits S1 NON UE-ASSOCIATED MOVECOMPLETE through the new SCTP association as the “start marker.”

In step 6, after receiving a first non UE-associated message or S1 NONUE-ASSOCIATED MOVE COMPLETE from the new SCTP association, thedestination node informs higher layer that the non UE-associatedsignaling connections may be resumed, and all the outgoing signals willbe directed to the new SCTP association

An alternative procedure for decreasing the delay of moving is:

For the destination node, after transmitting non UE-associated signal“S1 NON UE-ASSOCIATED MOVE CONFIRM” through the old SCTP association(step 4), it directly informs higher layer that the non UE-associatedsignaling connection may be resumed (step 6), and all the outgoingsignals will be directed to the new SCTP association.

For the originating node, after transmitting non UE-associated signal“S1 NON UE-ASSOCIATED MOVE REQUEST” through the old SCTP association tothe destination node (step 2), if it receives new messages from thedestination node through the new SCTP association, it will not forwardthese new messages to higher layer until “S1 NON UE-ASSOCIATED MOVECONFIRM” is received from the old SCTP association (step 4). Also,eventual transmission of S1 NON UE-ASSOCIATED MOVE COMPLETE (step 5a) isomitted.

2.6 Error Case, All Embodiments

FIG. 29 illustrates an example of an error case for both of theabove-discussed embodiments. That is, FIG. 29 illustrates an example ofmoving non UE-associated signaling between SCTP associations (failurecase). Steps 1-3 are the same as the successful case described above(step 1 is omitted in the case of embodiment 2). In step 4, if erroroccurs due to some reason, e.g. invalid MME S1 connection bundle ID, MMEtransmits “S1 NON UE-ASSOCIATED MOVE REJECT” to eNB, informing that themove is aborted. In step 4, after receiving “S1 NON UE-ASSOCIATED MOVEREJECT”, eNB informs higher layer that the non UE-associated signalingmay be resumed, and all the outgoing signals will continue through theoriginal SCTP association.

3 ADDITIONAL EXAMPLES

The solutions described above may be implemented in any suitable manner.FIGS. 30-39 provide additional examples.

FIG. 30 is a flow chart illustrating an example of a method forestablishing multiple SCTP associations per S1AP connection, inaccordance with certain embodiments of the present disclosure.

At step 3004 the method establishes a first SCTP association for an S1APconnection between a first network node and a second network node, atstep 3008 the method connects the S1AP connection between the firstnetwork node and the second network node, and at step 3012 the methodestablishes a second SCTP association for the S1AP connection betweenthe first network node and the second network node. Examples of addingan SCTP association are described above with respect to FIGS. 14-16.Examples of identifiers that can be used for the SCTP associations aredescribed above with respect to FIG. 13 and Tables 1-3. For simplicity,FIG. 30 provides an example in which two SCTP associations areestablished for the S1AP connection. However, in other embodiments, morethan two SCTP associations can be established (e.g., 3, 4, 5, . . . Nassociations). In certain embodiments, connecting the S1AP connection instep 3008 can be performed according to procedures set forth in existingor future evolutions of 3GPP LTE or 5G.

Optionally, the method may include steps for moving traffic among SCTPassociations. For example, at step 3016, the method determines to movesome or all traffic from the first SCTP association to the second SCTPassociation. The determination to move the traffic may be for thepurposes of load balancing, hardware maintenance, hardware expansion,network slicing, or other reason.

At step 3020, the method moves the traffic from the first SCTPassociation to the second SCTP association. The traffic can include UEassociated and/or non-UE associated S1AP control signaling. Examples ofmethods for moving traffic are discussed above with respect to FIGS.22-29.

At step 3024, the method optionally deletes the first SCTP association.As an example, all of the traffic may be moved from the first SCTPassociation in order to perform maintenance on hardware used by thefirst SCTP association. After the traffic has been moved, the first SCTPassociation can be deleted. Examples of methods for deleting an SCTPassociation are discussed above with respect to FIGS. 17-20. In otherembodiments, the method need not delete the first SCTP association, forexample, of some of the traffic stays on the first SCTP association forload-balancing or network slicing purposes.

FIG. 31 is a flow chart illustrating an example of a method forassociating UE-associated signaling streams and non-UE associatedsignaling streams with SCTP associations, in accordance with certainembodiments of the present disclosure. At step 3104, the methoddedicates the first SCTP association to one or more user equipment (UE)associated signaling streams, each UE associated signaling streamassociated with a respective UE. At step 3108, the method dedicates thesecond SCTP association to a non-UE associated signaling stream. FIG.12, discussed above, illustrates an example in which the SCTPassociation depicted at the top of the S1AP signaling connection hasbeen dedicated to non-UE associated signaling and the SCTP associationdepicted at the bottom of the S1AP connection has been dedicated toUE-associated signaling.

FIG. 32 is a flow chart illustrating an example of a method forassociating UE-associated signaling streams and non-UE associatedsignaling streams with SCTP associations, in accordance with certainembodiments of the present disclosure. At step 3204, the methodassociates a first set of one or more user equipment (UE) associatedsignaling streams with the first SCTP association and a second set ofone or more UE associated signaling streams with the second SCTPassociation. Each UE associated signaling stream is associated with arespective UE. At step 3208, the method associates a first non-UEassociated signaling stream with the first SCTP association and a secondnon-UE associated signaling stream with the second SCTP association. Anexample of such associations is illustrated in FIG. 11, discussed above.

FIG. 33 is a signal diagram illustrating an example of a method formoving traffic between SCTP associations, in accordance with certainembodiments of the present disclosure. The messages shown in FIG. 33 maybe exchanged between network node A and network node B. The networknodes are given the non-limiting designations “A” and “B” for thepurposes of explaining communications between the nodes. Thus, networknode A may perform the functionality of a first network node and networknode B may perform the functionality of a second network node, or viceversa. In certain embodiments, network node A may be an eNB and networknode B may be an MME, or vice versa. FIGS. 22-24 and 26-28, discussedabove, provide additional details of certain embodiments of the methodfor moving traffic between SCTP associations shown in FIG. 33.

At step 3304, network node A and network node B communicate S1APmessages via a first SCTP association. At step 3308, network node Astops all outgoing S1AP messages on the first SCTP association. Forexample, network node A may stop all outgoing S1AP messages in responseto a determination to move traffic to a second SCTP association (seee.g., step 3016 of FIG. 30). All outgoing S1AP messages on the firstSCTP association may refer to messages for a multiple UE-associatedsignaling connections (see e.g., FIG. 22), a single UE-associatedsignaling connection (see e.g., FIGS. 23-24), or a non-UE associatedsignaling connection (see e.g., FIGS. 26-28). Network node A maygenerate a first stop marker to identify the last message beingtransmitted by network node A on the first SCTP association.

At step 3312, network node A sends network node B a request to move fromthe first SCTP association to the second SCTP association. The requestcomprises the first stop marker indicating the last message beingtransmitted by network node A on the first SCTP association.

At step 3316, in response to receiving the request to move from thefirst SCTP association to the second SCTP association in step 3312,network node B stops all outgoing S1AP messages on the first SCTPassociation. Network node B may generate a second stop marker toidentify the last message being transmitted by network node B on thefirst SCTP association.

At step 3320, network node B sends to network node A a confirmation tomove the first SCTP association to the second SCTP association. Theconfirmation comprises the second stop marker indicating the lastmessage being transmitted by network node B on the first SCTPassociation.

In response to receiving the confirmation from network node B, networknode A sends network node B an indication that the move to the secondSCTP association is complete. The indication may optionally be sentexplicitly (e.g., by sending a completion message, step 3324) orimplicitly (e.g., by sending network node B S1AP messages occurringafter the first stop marker via the second SCTP association, step 3328).After moving from the first to the second SCTP association, networknodes A and B may send outgoing S1AP messages and receive incoming S1APmessages via the second SCTP association (step 3328).

FIG. 34 is a flow chart illustrating an example of a method foridentifying an SCTP association, in accordance with certain embodimentsof the present disclosure. At step 3404, the method determines aplurality of identifiers associated with the first SCTP association andat step one or more of the identifiers. For example, the identifiers maybe used to establish, delete, or move a signaling stream, or toestablish, delete, or reset the first SCTP association. Examples ofidentifiers that can be exchanged include one or more of: a firstconfiguration identifier that a first network node (e.g., network nodeA) associates with an S1AP connection, a second configuration identifierthat a second network node (e.g., network node B) associates with theS1AP connection, a first bundle identifier that the first network nodeassociates with a first SCTP association (or with a signaling stream ofthe first SCTP association), and a second bundle identifier that thesecond network node associates with the first SCTP association (or witha signaling stream of the first SCTP association). Further details ofthe identifiers are discussed above, e.g., with respect to FIG. 13 andTables 1-3. Example messaging using the identifiers is shown in FIGS.14-29.

FIG. 35 illustrates an example of a wireless device 110, and FIGS. 36-37illustrate examples of network nodes, e.g., radio access node 120 andcore network node 130, respectively, which may be suitably operative inaccordance with certain embodiments. As discussed above, examples of theradio access nodes 120 include an access point, a radio access point, abase station, a base station controller, an eNodeB (eNB), a Home eNB(HeNB), a HeNB Gateway (HeNB GW). A radio access node 120 may compriseany entity capable of at least receiving or transmitting radio signalswithin a radio network and/or cell/sector, or both. As discussed above,examples of core network node 130 include a Mobile Management Entity(MME), Serving Gateway (S-GW), or other device that supportsestablishing and controlling one or more SCTP-S1AP connections between aradio access node and an evolved packet core node, either directly orindirectly, and interacting with radio access nodes to carry outembodiments of the proposed solution(s) described herein. A core networknode 130 may comprise any entity capable of communicating andestablishing connections with a radio access.

In general, wireless device 110 and network nodes (e.g., 120 and 130)may each comprise one or more interfaces (such as one or moretransceivers that facilitate transmitting and receiving wireless signalsand/or one or more network interfaces for wireline communication),processing circuitry (which may include one or more processors thatexecute instructions to provide some or all of the functionalitydescribed as being provided by the particular node), and memory thatstores instructions executed by the processing circuitry. For example,FIG. 35 illustrates wireless device 110 as comprising transceiver 112,processing circuitry 114 a-n, and memory 116 a-n. FIG. 36 illustrates anetwork node (radio access node 120) as comprising transceiver 122,processing circuitry 124 a-n, memory 126 a-n, and network interface(s)128 a-n. FIG. 37 illustrates a network node (core network node 130) ascomprising network interface(s) 132 a-n, processing circuitry 134 a-n,and memory 136 a-n.

Processing circuitry (e.g., 114, 124, 134) may comprise one or moreprocessors. A processor may comprise any suitable combination ofhardware and software implemented in one or more modules to executeinstructions and manipulate data to perform some or all of the describedfunctions of the respective node. For example, processing circuitry 124and/or 134 of network nodes 120 and/or 130 may be configured to performsome or all of the methods described with respect to FIGS. 14-34. Insome embodiments, the processor may include, for example, one or morecomputers, one or more central processing units (CPUs), one or moremicroprocessors, one or more applications, processing circuitry, and/orother logic.

Memory (e.g., 116, 126, 136) is generally operable to storeinstructions, such as a computer program, software, an applicationcomprising one or more of logic, rules, algorithms, code, tables, etc.and/or other instructions capable of being executed by a processor.Examples of memory include computer memory (for example, Random AccessMemory (RAM) or Read Only Memory (ROM)), mass storage media (forexample, a hard disk), removable storage media (for example, a CompactDisk (CD) or a Digital Video Disk (DVD)), and/or or any other volatileor non-volatile, non-transitory computer-readable and/orcomputer-executable memory devices that store information.

In an embodiment, a non-transitory computer-readable medium comprisesmachine-readable computer instructions. The machine-readable computerinstructions are executed by a processor, which causes the network node(e.g., node 120 or 130) to support, for example, multiple SCTPassociations per S1AP connection. In certain embodiments, themachine-readable computer instructions executed by the processor furthercause the network node (e.g., node 120 or 130) to perform the methodsdescribed herein for moving a S1AP signaling connection between SCTPassociations.

Embodiments of a network node 120 include multiple network interfaces128 a-n for multiple SCTP associations per S1AP connection. Similarly,embodiments of network node 130 include multiple network interfaces 132a-n for multiple SCTP associations per S1AP connection.

Embodiments of the nodes may include additional components beyond thoseshown in FIGS. 35-37 that may be responsible for providing certainaspects of the network node's functionality, including any of thefunctionality described herein and/or any additional functionality(including any functionality necessary to support the solution describedherein). The various different types of network nodes may includecomponents having the same physical hardware but configured (e.g., viaprogramming) to support different functionality, or may represent partlyor entirely different physical components.

FIG. 38 provides examples of modules of a wireless device 110. Incertain embodiments, wireless device 110 may include any one or more of:determining module 3810, communication module 3820, receiving module3830, input module 3840, display module 3850, and/or other suitablemodules. The functionality of the modules may be integrated in a singlecomponent or separated among several components in any suitable manner.In certain embodiments, one or more of the modules may be implementedusing one or more processing circuitry 114 described with respect toFIG. 35.

Determining module 3810 may perform the processing functions of wirelessdevice 110 (including any of the UE functionality to support theabove-described embodiments). Determining module 3810 may include or beincluded in one or more processors, such as processing circuitry 114described above in relation to FIG. 35. Determining module 3810 mayinclude analog and/or digital circuitry configured to perform any of thefunctions of determining module 3810 and/or processing circuitry 114described above. The functions of determining module 3810 describedabove may, in certain embodiments, be performed in one or more distinctmodules.

Communication module 3820 may perform the transmission functions ofwireless device 110. As one example, communication module 3820 maycommunicate signals to network node 120. Communication module 3820 mayinclude a transmitter and/or a transceiver, such as transceiver 112described above in relation to FIG. 35. Communication module 3820 mayinclude circuitry configured to wirelessly transmit messages and/orsignals. In particular embodiments, communication module 3820 mayreceive messages and/or signals for transmission from determining module3810. In certain embodiments, the functions of communication module 3820described above may be performed in one or more distinct modules.

Receiving module 3830 may perform the receiving functions of wirelessdevice 110. For example, receiving module 3830 may receive signals fromnetwork node 120. Receiving module 3830 may include a receiver and/or atransceiver, such as transceiver 112 described above in relation to FIG.35. Receiving module 3830 may include circuitry configured to wirelesslyreceive messages and/or signals. In particular embodiments, receivingmodule 3830 may communicate received messages and/or signals todetermining module 3810. The functions of receiving module 3830described above may, in certain embodiments, be performed in one or moredistinct modules.

Input module 3840 may receive user input intended for wireless device110. For example, the input module may receive key presses, buttonpresses, touches, swipes, audio signals, video signals, and/or any otherappropriate signals. The input module may include one or more keys,buttons, levers, switches, touchscreens, microphones, and/or cameras.The input module may communicate received signals to determining module3810. The functions of input module 3840 described above may, in certainembodiments, be performed in one or more distinct modules.

Display module 3850 may present signals on a display of wireless device110. Display module 3850 may include the display and/or any appropriatecircuitry and hardware configured to present signals on the display.Display module 3850 may receive signals to present on the display fromdetermining module 3810. The functions of display module 3810 describedabove may, in certain embodiments, be performed in one or more distinctmodules.

Determining module 3810, communication module 3820, receiving module3830, input module 3840, and display module 3850 may include anysuitable configuration of hardware and/or software. Wireless device 110may include additional modules beyond those shown in FIG. 38 that may beresponsible for providing any suitable functionality, including any ofthe functionality described above and/or any additional functionality(including any functionality necessary to support the various solutionsdescribed herein).

FIG. 39 provides examples of modules of a network node, such as a radioaccess node 120 (e.g., eNB, gNB, etc.) or a core network node 130 (e.g.,MME, S-GW, etc.). In certain embodiments, the network node may includeany one or more of: determining module 3910, communication module 3920,receiving module 3930, and/or other suitable modules. The functionalityof the modules may be integrated in a single component or separatedamong several components in any suitable manner. In certain embodiments,one or more of the modules may be implemented using one or moreprocessing circuitry (e.g., 124 or 134) described with respect to FIGS.36-37.

Determining module 3910 may perform the processing functions of thenetwork node (including any of the eNB or MME functionality to supportthe above-described embodiments). Examples of processing functions thatmay be performed by determining module 3910 include determining toadd/establish, delete, or reset an SCTP association for an S1APconnection or determining to add/establish, delete, or move an SCTPsignaling stream. Determining module 3910 may make furtherdeterminations to support the preceding functionality, such asdetermining identifiers associated with the SCTP association.Determining module 3910 may include or be included in one or moreprocessors, such as processing circuitry (e.g., 124 or 134) describedabove in relation to FIGS. 36-37. Determining module 3910 may includeanalog and/or digital circuitry configured to perform any of thefunctions of determining module 3910 and/or processing circuitry (e.g.,124 or 134) described above. The functions of determining module 3910described above may, in certain embodiments, be performed in one or moredistinct modules.

Communication module 3920 may perform the sending functions of a networknode (e.g., 120 or 130). As one example, communication module 3920 maycommunicate signals to another network node, such as signals comprisingany of the messages shown in one or more of FIGS. 14-29 and 33.Communication module 3920 may include any suitable interface forcommunicating signals, such as a network interface (e.g., 128 or 132)for wired communication and/or a transceiver (e.g., 122) for wirelesscommunication, as described above in relation to FIGS. 36-37.Communication module 3920 may include circuitry configured to transmitmessages and/or signals. In particular embodiments, communication module3920 may receive messages and/or signals for transmission fromdetermining module 3910. In certain embodiments, the functions ofcommunication module 3920 described above may be performed in one ormore distinct modules.

Receiving module 3930 may perform the receiving functions of the networknode (e.g., 120 or 130). For example, receiving module 3930 may receivesignals from another network node, such as signals comprising any of themessages shown in one or more of FIGS. 14-29 and 33. Receiving module3930 may include any suitable interface for receiving signals, such as anetwork interface (e.g., 128 or 132) for wired communication and/or atransceiver (e.g., 122) for wireless communication, as described abovein relation to FIGS. 36-37. In particular embodiments, receiving module3930 may communicate received messages and/or signals to determiningmodule 3910. The functions of receiving module 3930 described above may,in certain embodiments, be performed in one or more distinct modules.

Determining module 3910, communication module 3920, and receiving module3930 may include any suitable configuration of hardware and/or software.The network node (e.g., 120 or 130) may include additional modulesbeyond those shown in FIG. 39 that may be responsible for providing anysuitable functionality, including any of the functionality describedabove and/or any additional functionality (including any functionalitynecessary to support the various solutions described herein).

An advantage of certain embodiments is that they eliminate resetting ofall UEs associated to S1AP in case of re-establishment of S1AP transportlayer (SCTP), for example, during hardware maintenance/expansion, as theSCTP association may now be disconnected and reconnected to S1AP withoutremoval of existing S1AP configuration data. An additional advantage isthat certain embodiments increase S1AP robustness in the case ofsoftware failure (SW_failure). That is, the number of affected UEs willbe decreased when a SCTP instance fails. A further advantage of certainembodiments is that they allow for S1AP signaling load distribution byspreading signaling load over multiple SCTP connections eventuallyserved by different processors. Another advantage of certain embodimentsis that they increase flexibility of load distribution capability in anS1AP with multiple SCTP associations, where a single S1AP signalingconnection may be freely moved between SCTP association without causingany disturbance on the interface in terms of in-order delivery, lostmessage, or reset of any SCTP association. Certain embodiments may haveall, some, or none of these advantages. Other advantages may be apparentto one of ordinary skill in the art.

Modifications and other variants of the described embodiment(s) willcome to mind to one skilled in the art having the benefit of theteachings presented in the foregoing descriptions and the associateddrawings. Therefore, it is to be understood that the embodiment(s)is/are not to be limited to the specific examples disclosed and thatmodifications and other variants are intended to be included within thescope of this disclosure. Although specific terms may be employedherein, they are used in a generic and descriptive sense only and notfor purposes of limitation.

Modifications, additions, or omissions may be made to the aboveembodiments and other methods disclosed herein without departing fromthe scope of the invention. The methods may include more, fewer, orother steps. Additionally, steps may be performed in any suitable order.In certain embodiments, the methods disclosed herein may be implementedusing a computer program product. The computer program product comprisesa non-transitory computer readable storage medium having computerreadable program code embodied in the medium, the computer readableprogram code comprising computer readable program code to perform thesteps of the methods.

Modifications, additions, or omissions may be made to the systems andapparatuses disclosed herein without departing from the scope of theinvention. The components of the systems and apparatuses may beintegrated or separated. Moreover, the operations of the systems andapparatuses may be performed by more, fewer, or other components.Additionally, operations of the systems and apparatuses may be performedusing any suitable logic comprising software, hardware, and/or otherlogic.

Although this disclosure has been described in terms of certainembodiments, alterations and permutations of the embodiments will beapparent to those skilled in the art. The embodiments described hereinmay be combined with each other in any way. Although some embodimentshave been described with reference to certain radio access technologies,any suitable radio access technology (RAT) may be used, such as 5G, longterm evolution (LTE) (FDD or TDD), LTE-Advanced, UTRA, UMTS, HSPA, GSM,cdma2000, WiMax, and WiFi. Moreover, various embodiments may supportsingle-RAT or multi-RAT configurations. Accordingly, the abovedescription of the embodiments does not constrain this disclosure. Otherchanges, substitutions, and alterations are possible without departingfrom the spirit and scope of this disclosure.

1. A method for use by a network node in a Radio Access Network (RAN), the method comprising: establishing a first Stream Control Transmission Protocol (SCTP) association for an application protocol connection with a core network node; establishing a second SCTP association for the application protocol connection with the core network node; and moving a user equipment (UE) associated signaling stream from the first SCTP association to the second SCTP association.
 2. The method of claim 1, further comprising: dedicating the first SCTP association to one or more UE associated signaling streams, wherein each UE associated signaling stream associated with a respective UE.
 3. The method of claim 1, wherein moving the UE associated signaling stream from the first SCTP association to the second SCTP association is performed in response to at least one of: a load balancing determination; hardware maintenance; hardware expansion; or a determination to perform network slicing.
 4. The method of claim 1, wherein moving the UE associated signaling stream includes receiving a message from the core network node, the message indicating a network node identifier corresponding to the UE associated signaling stream.
 5. The method of claim 1, wherein moving the UE associated signaling stream includes receiving a message from the core network node, the message indicating a core network node identifier corresponding to the UE associated signaling stream.
 6. The method of claim 1, further comprising: associating a first set of one or more UE associated signaling streams with the first SCTP association; and associating a second set of one or more UE associated signaling streams with the second SCTP association.
 7. The method of claim 1, further comprising: dedicating an SCTP association to a non-UE associated signaling stream.
 8. A network node, comprising: a memory to store instructions; processing circuitry to execute the instructions to perform operations comprising: establishing a first Stream Control Transmission Protocol (SCTP) association for an application protocol connection with a core network node; establishing a second SCTP association for the application protocol connection with the core network node; and moving a user equipment (UE) associated signaling stream from the first SCTP association to the second SCTP association.
 9. The network node of claim 8, the operations further comprising: dedicating the first SCTP association to one or more UE associated signaling streams, wherein each UE associated signaling stream associated with a respective UE.
 10. The network node of claim 8, wherein moving the UE associated signaling stream from the first SCTP association to the second SCTP association is performed in response to at least one of: a load balancing determination; hardware maintenance; hardware expansion; or a determination to perform network slicing.
 11. The network node of claim 8, wherein moving the UE associated signaling stream includes receiving a message from the core network node, the message indicating a network node identifier corresponding to the UE associated signaling stream.
 12. The network node of claim 8, wherein moving the UE associated signaling stream includes receiving a message from the core network node, the message indicating a core network node identifier corresponding to the UE associated signaling stream.
 13. The network node of claim 8, further comprising: associating a first set of one or more UE associated signaling streams with the first SCTP association; and associating a second set of one or more UE associated signaling streams with the second SCTP association.
 14. The network node of claim 8, further comprising: dedicating an SCTP association to a non-UE associated signaling stream.
 15. A non-transitory computer readable storage medium having computer readable program code, the computer readable program code executed by a network node to perform operations comprising: establishing a first Stream Control Transmission Protocol (SCTP) association for an application protocol connection with a core network node; establishing a second SCTP association for the application protocol connection with the core network node; and moving a user equipment (UE) associated signaling stream from the first SCTP association to the second SCTP association.
 16. The non-transitory computer readable storage medium of claim 15, the operations further comprising: dedicating the first SCTP association to one or more UE associated signaling streams, wherein each UE associated signaling stream associated with a respective UE.
 17. The non-transitory computer readable storage medium of claim 15, wherein moving the UE associated signaling stream from the first SCTP association to the second SCTP association is performed in response to at least one of: a load balancing determination; hardware maintenance; hardware expansion; or a determination to perform network slicing.
 18. The non-transitory computer readable storage medium of claim 15, wherein moving the UE associated signaling stream includes receiving a message from the core network node, the message indicating a network node identifier corresponding to the UE associated signaling stream.
 19. The non-transitory computer readable storage medium of claim 15, wherein moving the UE associated signaling stream includes receiving a message from the core network node, the message indicating a core network node identifier corresponding to the UE associated signaling stream.
 20. The non-transitory computer readable storage medium of claim 15, further comprising: associating a first set of one or more UE associated signaling streams with the first SCTP association; and associating a second set of one or more UE associated signaling streams with the second SCTP association. 